PRODUCTION AND CHARACTERIZATION OF DRUM DRIED AND VACUUM OVEN DRIED AMBARELLA

April 16, 2019 Critical Thinking

PRODUCTION AND CHARACTERIZATION OF DRUM DRIED AND VACUUM OVEN DRIED AMBARELLA, BINTANGOR ORANGE AND SARAWAK PINEAPPLE POWDER
SHALINI CHAN YIN FOONG
B. Sc (Hons.) FOOD SCIENCE WITH NUTRITION
FACULTY OF APPLIED SCIENCES
UCSI UNIVERSITY
2018
ACKNOWLEDGEMENT
First and foremost, I would like to thank UCSI University for providing me with the facilities and equipment for me to successfully carry out my final year project. Throughout this final year project, I have gained and expanded my knowledge on various techniques and information apart from those studied in the classroom. Most importantly, I experienced various hands-on techniques which will be a great advantage for me in the future when I further my studies or when I start to work in the industries.
Next, I would like to thank my supervisor and co-supervisor of my final year project, Assistant Professor Dr. Pui Liew Phing and Associate Professor Dr. Nyam Kar Lin. I would like to express my gratitude for their unconditional guidance and words of advice from the starting until the end of my project. With their support, I was able to learn from my mistakes and improve myself in various aspects. I am also truthfully grateful and thankful to them for their patience in handling my mistakes and delays throughout the project.
Furthermore, I am also pleased and thankful to the lab staff, Mr Dewa, Mr Chris, Ms Nelly, and Mr Saras, who taught me how to operate and showed me where to obtain the equipment. Without their help, I would have faced difficulties in navigating the lab by my own. Moreover, the experience they have in handling the equipment had allow me to carry out the experiments and obtain successful results.
In addition, I would specially like to thank Universiti Putra Malaysia (UPM) for allowing me to use the drum dryer and vacuum oven dryer which were placed at their food technology and engineering laboratories. I would not have been able to carry out my final year project without these equipment. Most importantly, by learning how to use both of these equipment I had gain my knowledge on hands-on techniques apart from the ones in UCSI University.
Last but not least, I would like to thank my family and friends for all their continuous encouragement and support especially throughout this entire project. During these difficult times, they never fail to comfort and cheer me up.
DECLARATION OF ORIGINALLY AND EXCLUSIVENESS
I hereby declare that the thesis is based on my original work except for quotations and citations, which have been duly acknowledged. I also declare that it has not been previously or concurrently submitted for any other degree at UCSI University or other institutions.

___________________________
SHALINI CHAN YIN FOONG
Date:
DECLARATION OF SUPERVISOR AND EXAMINERS
We, supervisor and examiners of this student, are satisfied with all the corrections, addition and rewriting done to this thesis as agreed upon in the oral examination and it is in accordance to the faculty’s requirements.

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Supervisor: Assistant Professor Dr. Pui Liew PhingSignature:
Co-supervisor: Associate Professor Dr. Nyam Kar LinSignature:
Examiner 1:Associate Professor Dr. Ivan Ho Chun WaiSignature:
Examiner 2:Assistant Professor Dr. Wong Chen WaiSignature:
Certified by:
_____________________________
ASSOC. PROF. DR. BIMO ARIO TEJO
Dean
Faculty of Applied Sciences,
UCSI University
Date:
ABSTRACT
This study aimed to compare the effects of drum drying and vacuum oven drying on the physicochemical properties and reconstituted properties of ambarella, Bintangor orange and Sarawak pineapple powder. The physicochemical properties of the powders were determined, where the colour analysis, moisture content, water activity, hygroscopicity, degree of caking, wettability, flowability, water solubility index and total colour changed were analysed. Whereas, the reconstituted properties of powder namely total colour change, beta carotene content and vitamin C content were determined. Ambarella, Bintangor orange and Sarawak pineapple purees used in both the different drying methods were incorporated with 50% (v/w) of maltodextrin. Results showed the process yield of vacuum oven dried powder were higher with values of 36.51%, 43.72% and 38.80% than drum dried powder with values of 20.79%, 31.13% and 21.21% for ambarella, Bintangor orange and Sarawak pineapple respectively. Although drum dried powder of ambarella, Bintangor orange and Sarawak pineapple had lower moisture content with values of 4.17%, 4.57% and 4.35%, nevertheless the drum dried powder also had lower water activity with values of 0.307, 0.343 and 0.377 and better flowability with values of 37.81°, 33.27°and 37.57°.For vacuum oven dried powder of ambarella, Bintangor orange and Sarawak pineapple had lower hygroscopicity with values of 0.25%, 0.34% and 0.22%, had a lower degree of caking with values of 6.53%, 10.36% and 5.89% and a shorter time taken to wet the powder with values of 49.07s, 40.52s and 33.78s. At the same time vacuum oven dried powder had a higher solubility rate such as 19.51%, 23.25% and 23.64% for ambarella, Bintangor orange and Sarawak pineapple. However, drum dried ambarella powder with a value of 22.79% had a better solubility then vacuum oven dried ambarella powder. Vacuum oven drying method had lesser total colour change with values of 39.90, 32.85 and 19.51, at the same time it is better in retaining the beta carotene with values of 27.65 µg/g, 67.41 µg/g and 11.37 µg/g and vitamin C content with values of 19.72 mg/g, 16.34 mg/g and 15.13 mg/g in the ambarella, Bintangor orange and Sarawak pineapple powder. Vacuum oven drying had positive effects on both physicochemical and reconstituted properties of fruit powder rather than drum drying. This study is important in choosing an appropriate drying method for further application of fruit powder.

TABLE OF CONTENTS
Page
ACKNOWLEDGEMENT I
DECLARATION OF ORIGINALITY AND EXCLUSIVENESS ii
DECLARATION OF SUPERVISOR AND EXAMINERS iii
ABSTRACT iv
TABLE OF CONTENTS v
LIST OF TABLES ix
LIST OF FIGURES xi
LIST OF EQUATIONS xii
LIST OF ABBREVIATIONS AND SYMBOLS xiii
Chapter IINTRODUCTION 1
1.1GENERAL OVERVIEW 1
1.2OBJECTIVES 4

Chapter IILITERATURE REVIEW 5
2.1FRUITS 5

2.1.1Ambarella 5
Background 5
Nutrient Composition 6
Common Usage 7
Bintangor Orange 8
Background 8
Nutrient Composition 9
Common Usage 10
Sarawak Pineapple 11
Background 11
Nutrient Composition 12
Common Usage 13
2.2DRYING 15
2.2.1Drum Drying 16
2.2.2Vacuum Oven Drying 19
2.3MALTODEXTRIN 21
2.4PHYSICOCHEMICAL ANALYSIS 21
2.4.1Colour Analysis 21
2.4.2Moisture Content 22
2.4.3Water Activity 23
2.4.4Hygroscopicity 23
2.4.5Degree of Caking 24
2.4.6Wettability 24
2.4.7Flowability 25
2.4.8Water Solubility Index (WSI) 25
2.5RECONSTITUTION ANALYSIS 26
2.5.1Beta Carotene Content 26
2.5.2Vitamin C Content 27
Chapter IIIMATERIAL AND METHOD 28
3.1MATERIALS 28
3.1.1Preparation of Fruit Samples 28
3.1.2Chemicals and Reagents 28
3.1.3Apparatus and Equipment 28
3.2PREPARATION OF SAMPLES AND DRYING PROCESS 29
3.2.1Preparation of Fruit Puree 29
3.2.2Drum Drying 29
3.2.3Vacuum Oven Drying 30
3.3PROCESS YIELD 31
3.4PHYSICOCHEMICAL ANALYSIS OF POWDER 31
3.4.1Colour Analysis 31

3.4.2Moisture Content 32
3.4.3Water Activity 33
3.4.4Hygroscopicity 33

3.4.5Degree of Caking 34
3.4.6Wettability 34
3.4.7Flowability 35
3.4.8Water Solubility Index (WSI) 35
3.4.9Total Colour Change (?E) 35
3.5RECONSTITUTION ANALYSIS OF POWDER 36
3.5.1Total Colour Change (?E) 36
Beta Carotene Content 36
Preparation of Standard Solution and Standard Curve
Beta Carotene Content Analysis
3.5.3Vitamin C Content 38

Preparation and Standardization of Iodine Solution
Preparation of Starch Indicator Solution
Vitamin C Content Analysis
3.6STATISTICAL ANALYSIS 39
Chapter IVRESULT AND DISCUSSION 40
4.1PROCESS YIELD 40
4.2PHYSICOCHEMICAL ANALYSIS OF POWDER 41
4.2.1Colour Analysis 42
4.2.2Moisture Content 44
4.2.3Water Activity 46
4.2.4Hygroscopicity 47
4.2.5Degree of Caking 49
4.2.6Wettability 50
4.2.7Flowability 52
4.2.8Water Solubility Index (WSI) 53
4.2.9Total Colour Change (?E) 55
4.3RECONSTITUTION ANALYSIS OF POWDER 56
4.3.1Reconstituted Colour 56
4.3.2Total Colour Change (?E) 59
4.3.3Beta Carotene Content Analysis 59
4.3.4Vitamin C Content Analysis 61
Chapter VCONCLUSION 63

5.1CONCLUSION 63
5.2LIMITATION OF STUDY AND FUTURE 64
RECOMMENDATIONS
REFERENCES 65

APPENDICES 81
LIST OF TABLES
Table No. Page
2.1 Nutrients composition available per 100 g of edible portion of ambarella fruit 7
2.2 Nutrients composition available per 100 g of edible portion of Bintangor orange pulp 11
2.3 Nutrients composition available per 100 g of edible portion of Sarawak pineapple pulp 15
2.4 Different fruits dried by drum drying and vacuum oven drying 17
2.5 Different parameters used for drum drying on different fruit samples 20
2.6 Different parameters used for vacuum oven drying on different fruit samples 22
4.1 Process yield of drum dried and vacuum oven dried of ambarella, Bintangor orange and Sarawak pineapple powder 42
4.2 The colour of drum dried and vacuum oven dried of ambarella, Bintangor orange and Sarawak pineapple powder 44
4.3 Moisture content of drum dried and vacuum oven dried of ambarella, Bintangor orange and Sarawak pineapple powder 46
4.4 Water activity of drum dried and vacuum oven dried of ambarella, Bintangor orange and Sarawak pineapple powder 47
4.5 Hygroscopicity of drum dried and vacuum oven dried of ambarella, Bintangor orange and Sarawak pineapple powder 48
4.6 Degree of caking of drum dried and vacuum oven dried of ambarella, Bintangor orange and Sarawak pineapple powder 50
4.7 Wettability of drum dried and vacuum oven dried of ambarella, Bintangor orange and Sarawak pineapple powder 52
4.8 Flowability of drum dried and vacuum oven dried of ambarella, Bintangor orange and Sarawak pineapple powder 53
4.9 Water solubility index (WSI) of drum dried and vacuum oven dried of ambarella, Bintangor orange and Sarawak pineapple powder 54
4.10 Total colour change of drum dried and vacuum oven dried of ambarella, Bintangor orange and Sarawak pineapple powder 56
4.11 Colour of reconstituted of drum dried and vacuum oven dried of ambarella, Bintangor orange and Sarawak pineapple powder 59
4.12 Total colour change of reconstituted of drum dried and vacuum oven dried of ambarella, Bintangor orange and Sarawak pineapple powder 60
4.13 Beta carotene content of drum dried and vacuum oven dried of ambarella, Bintangor orange and Sarawak pineapple powder 61
4.14 Vitamin C content of drum dried and vacuum oven dried of ambarella, Bintangor orange and Sarawak pineapple powder 62
LIST OF FIGURES
Figure No. Page
2.1 Ambarella tree (left) and the ambarella fruit with seeds (right) 6
2.2 Bintangor orange tree (left) and the fruit with a cut open flesh (right) 9
2.3 Sarawak pineapple (left) and the leaves and fruits of plant (right) 14
2.4 Show single and double drum dryers 19
2.5 Show a vacuum oven dryer 21
3.1 Purees of ambarella (left), Bintangor orange (middle) and Sarawak pineapple (right) incorporated with 50% (v/w) maltodextrin 30
3.2 Drum dryer 31
3.3 Vacuum oven dryer 32
3.4 Hunter-Lab ColorFlex Ez colorimeter 33
3.5 Mettler Toledo halogen moisture analyzer 34
3.6 AquaLab water activity meter 34
3.7 Desiccator with its bottom part pre-filled with saturated sodium chloride solution 35
3.8 (a) Drum dried ambarella; (b) Drum dried Bintangor orange; (c) Drum dried Sarawak pineapple; (d) Vacuum oven dried ambarella; (e) Vacuum oven dried Bintangor orange; (f) Vacuum oven dried Sarawak pineapple 41
LIST OF EQUATIONS
Equation No. Page
3.1 Process yield (%) = Weight of drum dried or vacuum oven dried fruit powder (g)Weight of fruit purees g x 100% 32
3.2 Moisture content (%) = Weight of wet sample g- Weight of dry sample (g)Weight of wet sample g x 100% 33
3.3 Hygroscopicity (%) = Final weight of sample after one week g- Initial weight of sample (g)Initial weight of sample g x 100% 35
3.4 Degree of caking (%) = Final weight of sample g- Initial weight of sample (g)Initial weight of sample g x 100% 35
3.5 Angle of repose/ Flowability (°)
= tan-1Height of funnel from base cmRadius of sample on base cm x 100% 36
3.6 Water solubility index, WSI (%)
= Weight of dried supernatant (g)Initial weight of sample g x 100% 36
3.7 Total colour change, ?E* = (Lo* -L*)2+(ao* -a*)2+(bo* -b*)237
3.8 Total colour change, ?E* = (Lo* -L*)2+(ao* -a*)2+(bo* -b*)237
3.9 Volume of acetone required, mL
M1V1 = M2V2 38
3.10 Amount of vitamin C in fruit powders, mg/g M1V1n1= M2V2n240
LIST OF ABBREVIATIONS AND SYMBOLS
A
?Alpha
AAAscorbic acid
AGArabic gum
B
?Beta
b*Blueness or yellowness
C
cmCentimetre
D
°Degree
°CDegree Celsius
DEDextrose equivalency
DHADehydroascorbic acid
G
gGram
a*Greenness or redness
; or ;Greater than or smaller than
K
KcalKilocalorie
KgKilogram
KpaKilopascal
L
L*Lightness or darkness
LLitre
M
µgMicrogram
µmMicrometer
mMeter
mgMilligram
mLMilliliter
mmMillimeter
MMolar concentration
MDMaltodextrin
N
nmNanometer
P
%Percentage
R
RERetinol
rpmRevolutions per minute
S
sSeconds
SLSoy lecithin
T
?ETotal colour change
W
aw Water activity
WSI Water solubility index

Chapter I
INTRODUCTION
1.1GENERAL OVERVIEW
Fruits have always proven to be an essential source of dietary nutrients such as fibre vitamins and minerals of a balanced diet. Diets which are rich in fruits play a critical role in maintaining a healthier lifestyle, which may reduce the risk of certain diseases such as cancer and heart diseases (Boeing et al. 2012). Fruits are highly favoured by consumers because of the nutritional compositions, mineral and vitamin contents of the fruit which is responsible for their strong antioxidant activity (Siriamornpun et al. 2012). This helps prevent human cells and tissues from undergoing oxidative damage.
Keeping the fruits fresh is the best way to maintain its nutritional value, however most storage techniques requires low temperature, which is difficult to maintain throughout the distribution chain. Therefore, drying is a suitable method for food processing. Over 20% of the world highly perishable commodities are dried to increase the shelf-life and promote food security (Sagar and Suresh 2010). Fruits are dried to enhance storage stability, minimise packaging requirements and reduce transportation weight (Sagar and Suresh 2010). Drying is also known as dehydration is a process of removing the moisture content from the fruit at a specific level. According to Jangam et al. (2010), drying also ensures the properties of fruit is physically and chemically constant.

Furthermore, dehydration of fruits into powdered particles is an excellent way to extend the shelf life and reduces the volume of the fruit. One of the main aim of converting fruits into powder form is to maintain the functionality and stability of the ingredients until they are used (Fitzpatrick and Ahrne 2005). There are many different drying methods that have been invented such as freeze drying, drum drying, vacuum drying and spray drying to increase the productivity. At the same time, to have a better control of process hence increasing the product quality (Cui et al. 2018).
Drum drying applies the principle of drying by using an internally heated drum saturated with steam at high temperatures. A thin film of suspension is applied on the heated metal cylinders (drum), then thin films of dry solids are produced. In the end, the product is scraped from the drum’s surface in the form of flakes (Moore 2005). The performance of a drum dryer is influenced by the steam pressure, feed concentration, level of pool between the drums and the drum rotation speed (Pua et al. 2010). Drum drying is one of the most energy efficient drying methods used to dry high viscous or pureed foods such as baby foods, fruit and vegetable pulps (Tang et al. 2003). To add on, the disadvantages of fruit powders obtained by drum drying have an undesirable powder aroma and nutritional loss due to the high drying temperature used (Nindo and Tang 2007).
Vacuum oven drying is a unit operation where moisture from food products is removed by drying under sub-atmospheric pressure (Ratti 2009). The process of vacuum oven drying is distinctive from conventional drying because food products are dried at temperatures lower than atmospheric pressure thus resulting in a better product quality, reduce in processing temperature and a reduce in shrivelling (Torres et al. 2011). Under vacuum conditions, air and water vapour present in the food expands leading to a creation of puffed like structure. This further, enhance mass and heat transfer due to large area-to-volume ratio (Kim 2012). By drying food products in the absence of air, oxidation reactions are eliminated therefore the colour, structure and taste of the dried food is improved (Borquez et al. 2010). However, a major drawback of vacuum oven drying is the high cost of large scale production.

Ambarella (Spondias dulcis) also known as ‘hog plum’ belongs to the family of Anacardiaceae. Ambarella is one of the indigenous and seasonal fruit crops that are grown in tropical and sub-tropic regions such as Vietnam, Cambodia, South America, Sri Lanka, Indonesia and Malaysia. It is used for food purposes such as curry, sauces, salads and juices (Pushpakumara et al. 2000). In Malaysia and Indonesia ambarella is called as ‘kedondong’. Ambarella is an excellent source of vitamin C, folic acid and potassium which are recommended for women who are pregnant (Gunasena et al. 2003). The abundance in the production of ambarella during seasonal periods is not fully being utilized, hence it leads to wastage (Ranathunga et al. 2011). Therefore, preservation methods like drying is required to fully utilize the ambarella throughout the year for its nutritional compositions.

Citrus fruits are one of the world’s major fruit crops with global availability contributing to human diets (Liu et al. 2012). Bintangor orange (C. reticulate blanco) is a seasonal fruit and is widely grown in regions throughout Sarawak. The fruit of Bintangor orange is widely utilized in Sarawak, used as a food ingredient for local delicacies such as ‘rojak buah’ and are usually made into juices. The Bintangor orange consists of abundance of health benefits and sensory attributes in the oranges. The health benefits consists of anti-oxidant properties such as high availability flavonoids needed to prevent free radical generation and proper functioning of immune system (Kamran et al. 2009). Since, Bintangor orange is a seasonal fruit, the only way to make it available all year round and to reduce wastage of the fruit is by processing the fruits using drying methods.

The scientific name of pineapple is (Ananas comosus), which is from the family of Bromeliaceae. Pineapple is the third most important tropical fruit in the world after banana and citrus (Hemalatha and Anbuselvi 2013). Sarawak pineapple has exceptional juiciness, vibrant tropical flavor and immense health benefits. A mature pineapple fruit consists of fructose, citric acid, malic acid, vitamin A,B and C, also a protein digesting enzyme bromelin that has a wide range of application in food industry (Ketnawa et al. 2011). The main organic acids found in pineapple are malic acid and citric acid which may act as a natural antioxidant in the fruit (Belitz et al. 2009). It is consumed fresh, juiced, cooked and preserved. This fruit is highly perishable and can only be stored 4-5 days after harvested and it is seasonal. Therefore, preservation methods such as canning and drying need to be done in order to extent the shelf-life of the Sarawak pineapple.
To date, no previous study has investigated the effect of drum drying and vacuum oven drying on the physicochemical properties, reconstituted properties, beta carotene content and vitamin C content in ambarella, Bintangor orange and Sarawak pineapple powders. Hence, the aim of this research is to compare the effects of drum drying and vacuum oven drying methods on analysis of physicochemical properties, reconstituted properties, beta carotene content and vitamin C content in ambarella, Bintangor orange and Sarawak pineapple powders
1.2OBJECTIVES
The aim of study were:
To determine the effects of drum drying and vacuum oven drying on the physicochemical properties in ambarella, Bintangor orange and Sarawak pineapple powder.
To compare the effects of different drying methods on the properties of reconstituted, beta carotene content and vitamin C content in ambarella, Bintangor orange and Sarawak pineapple powder.
Chapter II
LITERATURE REVIEW
2.1FRUITS
Ambarella
a)Background
Ambarella (Spondias dulcis) also more commonly known as hog plum, golden apple and Makok Faring (in Thai) is an indigenous tropical fruit originated from Malanesia and Polynesia of the South pacific (Rashtriya 2016). The tree is also well adapted in the Caribbean islands because of the humid tropical climate. Ambarella belongs to the Anacardiaceae family which is characterized by 9-25 pairs of glossy and oblong leaflets 9-10 cm long, which are finely toothed toward the apex. The fruit is an ellipsoid drupe about 4-10 cm long (0.45 kg), initially green and turns to golden yellow upon ripening (Minh and Oanh 2018). An ambarella fruit has a leathery stone which is ridged and bears hard fibres tends to project into the flesh. A best fruit has a waxy and glossy skin. Ambarella tree produces small and inconspicuous flowers.
Unripe fruits are hard, has a crunchy flesh that taste a little sour but tends to soften and becomes sweeter possessing a sweet-sour pineapple kind of flavour has the fruit becomes ripen (Ishak et al. 2005). The ripening of the fruit emits signifying volatile aroma of turpentine (Wong and Lai 1995). The types of volatile aromas includes 2-methyl butyrate, ethyl isovalerate, ethyl butyrate and trans-pinocarvcol (Fraga and Rezende 2001). Emission of volatile aromas act as an indicator of fruit ripening (El Hadi et al. 2013). The tree, fruit and leave are prone to various pesticide attacks. For example, in Indonesia, the ambarella leaves of the fruits are attack by larvae, spring-beetle (Rashtriya 2016). Therefore in order to maintain a good overall condition of the ambarella especially the fruit can be further dried and grind into powder to extent its storage life. In Peninsula Malaysia, ambarella is called as ‘kedondong’ by the Malays (Ishak et al. 2005 )and is grown in village gardens for consumption as shown in Figure 2.1, an ambarella tree growing in the area of the housing garden and an ambarella fruit.

Figure 2.1 Ambarella tree (left) and the ambarella fruit with seeds (right) (Google 2018)
b)Nutrient Composition
The main health benefits of ambarella is its fruit and leaves containing potential source of high natural polyphenol content, antimicrobial, cyctotoxic and thrombolytic and antioxidant activities (Islam et al. 2013). Antioxidant activity in ambarella is attributed by the hydroxyl groups of phenolic compounds which plays a role in stabilizing lipid peroxidation (Patel et al. 2011). Besides that, ambarella have been proven to have the presence of antimicrobial compound that exhibits antimicrobial activity against a broad spectrum of strains (Rahman and Islam 2013). Extracts from ambarella may contain antimicrobial compounds.
Ambarella is well known as a rich source of vitamin C and according to RNI states that 100 g of the fruit contains 60% of an individual daily vitamin C requirement. Vitamin C act as an important vitamin in the body to boost the immune system, used in throat infection, slowing down aging and accelerates wound healing process (Rashtriya 2016). The fruit contains abundance amounts of iron, calcium and high levels of phosphorus (Mohammed et al. 2011). Iron aids in the formation of red blood cells with the help of thiamine further production of red blood cells hence increasing the flow of oxygen throughout the body hence preventing anemia. The role of calcium and phosphorus in the fruit aids in maintain healthy bones and teeth.
The fruit is also loaded with vitamin A and carotene acts as antioxidant that can counteract free radicals from the body oxidation as well as pollution from outside (Ishak et al. 2005). Vitamin A tends to improve vision and plays an important role in visual perception. The compound of vitamin A known as retinol helps distribute images that are received by the retina of the eye (Rashtriya 2016). The nutrients available in 100 grams of edible portion of ambarella is shown in Table 2.1.
Table 2.1 Nutrients composition available per 100 g of edible portion of Ambarella fruit
Nutrient compositions References
Leung et al. (1972) Rashtriya (2016) Tiburski et al. (2011)
Water (g) 86.90 86.90 83.66
Energy (kcal) 46 46 65.42
Protein (g) 0.20 0.20 1.06
Fat (g) 0.10 0.10 0.62
Ash (g) 0.4 0.4 0.76
Carbohydrate (g) 12.40 12.40 13.90
Fibre (g) 1.10 1.10 1.87
Calcium (mg) 56 56 11.04
Phosphorus (mg) 67 67 32.85
Potassium (mg) 95 96 288.28
Sodium (mg) 1.0 – 5.55
Iron (mg) 0.30 0.30 0.33
Vitamin A (RE) – – 223
Thiamine (mg) 0.05 0.05 –
Riboflavin (mg) 0.20 0.20 –
Beta carotene (µg) 205 205 –
Vitamin C (mg) 36.0 36.0 30.0
c)Common Usage
Both ripe and unripe ambarella fruit can be consume directly or indirectly as a source of food. Ambarella is widely used as a food ingredient that is incorporated while cooking, eaten raw or mixed into pickles. Unripe ambarella fruits are eaten in curries, salads or made into pickles while ripe ones are normally processed into jams and juices. Various uses of kedondong in different field of expects. For instance, the fruit make into beverages, sherbets or mixed with other tropical fruit juices to enhance flavour, aroma and taste. The fruit are also consumed by herbivorous mammals such as deer and act as an animal feed to pigs (Rashtriya 2016). Besides that, the fruit is further processed usually for sweets, sparkling beverages, drink, nectar and syrups (Yenrina et al. 2017).
Young ambarella leaves can be eaten raw and the leaves are sometimes cook with meat for tenderizing the meat (Yahia 2011). The tree bark is processed into matches and boat of hollowed tree trunk because the wood is light and buoyant. Other parts of the fruit such as the leaves, barks and roots have high medical value for variety of diseases (Janick and Paull 2008). The leaves can be used as a wash for sore eyes while the roots are used as contraceptive. The tree bark of ambarella is used as a remedy for diarrhoea. Ambarella is a great choice for weight watchers as it does not contain saturated fat and cholesterol.
Bintangor Orange
a)Background
Orange is a type of citrus fruit originated from southeastern Asia, China (El-Otmani et al. 2011). Citrus fruits are one of the biggest fruit crops in the world. Bintangor orange is a seasonal type of citrus hybrids orange. It is a cross breed between (Citrus reticulata Blanco x Citrus aurantium L) (Hamilton 2007). Citrus reticulata Blanco is a type of tangerine known to have a sweet taste whereas, Citrus aurantium L is known to be a bitter and sour orange. Bintangor orange belongs to family of Rutaceae. Citrus is widely distributed in tropical and temperate regions of the planet (Ladaniya 2008). Citrus fruits are slow in growth, diseases, short season and short storage life (Mukhtar et al. 2005). These disadvantages can be overcome by processing the fresh fruit pulp into dried fruit.

The evergreen citrus species grows and produces fruit under a wide range of climate (El-Otmani et al. 2011). The trees of Bintangor orange are able to grow up to 6-20 meters tall and were planted in muddy paddy fields. The trees are heavy fruit bearers that could yield up to 2000 kg. The tree trunks are usually smooth and greyish-brownish in colour. The leaves are glossy and in measurement about 5-10 cm long ovate in shape. The flowers are small, has a waxy texture and its greenish-white in colour (Juan and Gene 2004). Diameters of the orange flowers are 2-5 cm, consisting five petals and the flowers are axillary, fragrant and often consists of both functional stamens and pistils. The fruit is round in shape and the outer skin of the fruit is slightly hard and green in colour. The flesh of the bintangor orange is orange in colour consisting of the sour-bitter juicy fruit pulp with the pith. The compound that is responsible to produce the typical bitterness for fruits is neohesperidin in sour oranges (Suntar et al. 2018). Some of the pulps are seedless while some contains white seeds. Figure 2.2 shows a Bintangor orange tree and an open fruit pulp of Bintangor orange.

Figure 2.2 Bintangor orange tree (left) and the fruit with a cut open flesh (right) (Google 2018)
b)Nutrient Composition
Bintangor orange is labelled as an excellent source of vitamin C, a good source of fibre and potassium. Having an orange a day helps to contribute 116% of the daily requirement for vitamin C (Parle and Chaturvedi 2012). Besides that, this fruit contains active phytochemicals such as carotenoids (beta carotene and lutein) and flavonoids that can protect the health by preventing the body from muscular degeneration and cognitive impairment in elderly (Johnson 2012). Moreover, polymethoxylated flavones such as tangeritin and nobiletin also helps in anti-inflammatory (Zhang et al. 2016), anti-allergic, antibacterial, antifungal and antiviral activities (Liu et al. 2012).

Oranges is able to decrease the risk of kidney stones because of the presence of citrates (Ladaniya 2008). According to a British Journal of Nutrition published that when a woman drinks daily at least half litre of orange juice their urine pH value increases. This lessen the risk of forming calcium oxalate stones (Honow et al. 2003). In addition, oranges is a rich source of dietary fibre serve to control the blood glucose levels and also has a positive effect in reducing cholesterol hence preventing atherosclerosis. The high fibre content in oranges also helps in constipation related problems (Parle and Chaturdevi 2012). The nutrient available per 100 grams of edible portion of Bintangor orange pulp is shown in Table 2.2.
c)Common Usage
In Sarawak especially in Bintangor and Sibu region, bintangor orange is widely used as a type of famous food ingredient. Bintangor oranges are make into orange juices as well incorporated into a dish called ‘rojak’ (Chua 2010). Besides that oranges are made into frozen orange juice concentrates. In addition, orange flavours are applied widely in the usage of beverages, confectionaries, flavouring and acidifying agent in foods (Karabiyikli et al. 2014). Besides that, famous marmalade spreads are made with oranges and the entire part of the fruit is used in which the peel of the orange is also incorporated into the marmalade. The peel of oranges contains significant amounts of phenolic acids and flavonoids, making it a potential material for food preservative and functional ingredient in alimentary products such as marmalade (Sicari et al. 2017).
For centuries and years, oranges such as Bintangor orange act as a folklore medicine. The whole plant including the leaves, flowers, seeds, fruits, peels and juices are used in traditional medication. The high content of vitamins, minerals and phytochemicals value makes it a valuable source (Parle and Chaturvedi 2012). The processing of citrus fruits like oranges eventually generates tons of organic waste such as seeds, peels and sometimes the pulps (Hiasa et al. 2014). This industrial by-products serve as an environmental problem to the planet. Therefore, citrus essential oils are obtained by the by-product of processing citrus fruits such as oranges, lemons and grapefruit. It is widely used in the perfume industry as well in aromatherapy for its fragrance because is regarded as safe (Fisher and Phillips 2008). Orange peel is also intended to use as an animal feed and biogas is highly desirable to reduce waste of agro by-products (Ajila et al. 2012).
Table 2.2 Nutrients composition available per 100 g of edible portion of Bintangor orange pulp
Nutrient compositions References
US Food and Drug Administration, USDA (2016) El-Otmani et al. (2011) Ministry of Health Malaysia (1997)
Water (g) 85.17 85.17 87.10
Energy (kcal) 53 53 49
Protein (g) 0.81 0.81 0.7
Fat (g) 0.31 0.31 0.5
Ash (g) 0.38 – 0.5
Carbohydrate (g) 13.34 13.34 10.40
Fibre (g) 1.8 1.8 0.8
Calcium (mg) 37 22 40.0
Magnesium (mg) 12 9 –
Phosphorus (mg) 20 18 19
Potassium (mg) 166.0 135 102.0
Vitamin A (µg RAE) 34 – –
Vitamin A (IU) 681 681 –
Thiamine (mg) 0.058 0.058 0.10
Riboflavin (mg) 0.036 0.036 0.0
Beta carotene (µg) 155 155 125.0
Vitamin C (mg) 26.7 26.7 39.6
2.1.3Sarawak Pineapple
a)Background
Pineapple (Ananas Comosus) is the only leading edible member of the family Bromeliaceae which bears edible fruit (Kudom and Kwapong 2010). Pineapples were originated from America. However, pineapple spread and grew around the globe in most tropical and subtropical countries such as Brazil, Thailand and Indonesia (Carlier et al. 2010). Pineapple is an important tropical fruit and is graded as the third most produced fruit in the world tropical production (Van de Poel et al. 2009). Several varieties of pineapples can be found in Malaysia. Three of the common varieties are Josephine, Morris and Sarawak pineapple which is also known as the Smooth Cayenne found in Peninsular Malaysia (Silva et al. 2008). The Malaysian Pineapple Industry Board (MPIB), stated that the state of Johor is the largest producer of pineapple. MPIB also stated that the pineapple industry is a substantial agricultural because it plays its part in the country’s earrings as one of the world pineapple suppliers (Chong 2013).
The Sarawak pineapple plant is a tropical, herbaceous, perennial monocot. It can grow up to 1-2 meters tall with spirally arranged leaves. The flowers of this plant tends to bloom on a terminal inflorescence, growing into a large edible fruit with a tuft of leaves on its apex (Kudom and Kwapong, 2010). Sarawak pineapple is able to grow vigorously and the fruit is much larger in sizes with an average size of 2-3 kilograms compared to other cultivars. The type of soil used to plant the plant will determine the size of the fruit. The plant that are planted on peat soil have slightly larger fruits compared to that are planted on mineral oils (Soloman et al. 2016). Sarawak pineapples are harvested at 130-150 days after blooming period (Sanewski and Scott 2000). The maturity of the fruit depends on few index such as measurement of size, weight, physical attributes such as colour, firmness and moisture content and some chemical attributes such as sugar and acid contents (Rosnah et. al. 2009). The flesh of Sarawak pineapple is pale in yellow, juicy, contains high percentage of acid 0.5-0.9% and sugar content of 12- 16° Brix. Figure 2.3 shows a pineapple fruit pulp and the pineapple plant.

Figure 2.3 Sarawak pineapple (left) and the leaves and fruits of plant (right) (Google 2018)
b)Nutrient Composition
According to the US Food and Drug Administration the nutrient compositions of smooth cayenne pineapples is a good source of minerals such as potassium and magnesium. Sarawak pineapple is also rich in vitamin B and C and also dietary fibre (De Ancos et al. 2016). Sarawak pineapple is low in caloric content in which every 100 g of Sarawak pineapple only contains 45.0 kcal. Sarawak pineapple is rich in potassium with 125.0 mg found in 100 g of Sarawak pineapple. Foods that are rich in potassium source tends to control the heart rate and decreasing the blood pressure level (Balch 2003).
Vitamin C is an essential nutrient for humans that they need to obtain from food. Daily consumption of vitamin C helps to protect the body from scurvy, increases immunity of the body and preventing free radicals from attacking a healthy cell. Free radicals causes atherosclerosis, diabetic heart disease and colon cancers (Joy 2010). Besides that, vitamin C supports the formation of collagen in bones, organs, cartilage and muscles (Sanchez et al. 2012). The Recommended Dietary Allowance (RDA) for vitamin C is 90 and 75 mg per day for adult males and females, respectively (IOM 2000). A consumption of a small portion of pineapple fruit daily will fulfil the requirement of this nutrient. Vitamin B1 (thiamine) found in pineapples aids in the conversion of carbohydrates into energy by the body cells. Thiamin triphosphate (TTP) is located in the nervous system and has an important role in different neurological processes (De Ancos et al. 2016). Manganese the existing source of essential mineral in pineapples plays a role in the formation of bones. The nutrient available per 100 grams of edible portion of Sarawak pineapple pulp is shown in Table 2.3.
c)Common Usage
The mature pineapple plant stems are collected and extracted for its bromelain juice. Bromelain is a type of enzyme used in meat tenderizing agent, stabilizing latex paints, chill proofing beer and leather-tanning process (Arshad et al. 2014). Certain countries, extracts the strong and silky fibre from the pineapple leaves for many purposes such as knitting the fibre into coarse textiles looking like grass cloth. Those time, it was used as threads in Borneo and Malacca. The stems and leaves are processed into papers and used to make (pina-cloth) in Philippines (Deliza et al. 2005). In Africa, the fibre is used to make into caps which were worn by tribal chiefs. Pineapple crowns act as an animal feed. If the crowns are not use for plantation, therefore it becomes the feeding material to horses (Joy 2010).
The pineapple peels contains huge amount of sugar contents that can be used for fermentation process. The peel can be recycled as a potential substrate for methanol and hydrogen generation (Choonut et al. 2014). The fresh pineapples are slice into small pieces and use in salads, desserts and blended into sauces. Sarawak pineapple is also use for further processing. For instance, canned pineapples, dehydrated pineapple, powdered pineapple (Gabas et al. 2007). In Caribbean pineapples are soak into salt solution before eating. The fermented pulp is made into a popular sweet meat called ‘nata de pina’ (Joy 2010).
Table 2.3 Nutrients composition available per 100 g of edible portion of Sarawak pineapple pulp
Nutrient compositions References
US Food and Drug Administration, USDA (2016a) De Ancos et al. (2016) Ministry of Health Malaysia (1997)
Water (g) 86.00 87.24 87.8
Energy (kcal) 50 45 45
Protein (g) 0.54 0.55 0.50
Fat (g) 0.12 0.13 0.10
Ash (g) 0.22 – 0.4
Carbohydrate (g) 13.12 11.82 10.6
Fibre (g) 1.40 1.4 0.6
Calcium (mg) 13.00 13.0 24.0
Magnesium (mg) 12.00 12.0 –
Phosphorus (mg) 8.00 9.0 6.0
Potassium (mg) 109.00 125.00 97.0
Vitamin A (µg RAE) 3 3 –
Vitamin A (IU) 58.00 52.00 –
Thiamine (mg) 0.079 0.078 0.1
Riboflavin (mg) 0.032 0.029 0.1
Beta carotene (µg) 35 – 270.0
Vitamin C (mg) 47.80 16.9 15.2
Sarawak pineapple fruit is high in phenolic compounds like tannic acid, sinapic acid, malic acid and p-hydroxybenzoic acid (Edwige et al. 2011). Phenolic compounds in the fruit tend to vigilantes many bioactive compounds that helps in the prevention of certain diseases. According to the U.S National Library of Medicine stated bromelain as a proteolytic digestive enzyme. Bromelain functions to help in digestion and anti-inflammatory properties. The proteins are digested by the enzyme bromelain which breaks the protein down into amino acids (Bartholomew et al. 2003) hence improving the digestion system.
DRYING
Drying is one of the oldest method of preserving of foods. For centuries, traditional and old drying methods are use such as sun drying and oven drying (Ahmed et al. 2013). Although traditional and old drying methods are less costly however, upon using these methods the weather condition and the poor performance of the drying methods need to be considered (Toshniwal and Karale 2013). Moreover, these methods of heat transfer leads the end product to have a poor quality and high risk of contamination.
Due to the drawback of traditional and old drying methods, therefore the development of new methods of drying are introduced being more reliable and effective. For instance, vacuum drying method, osmotic drying and drying by radiation (Ahmed et al. 2013). During the drying process, moisture is eliminated from the food material as a result of mass transfer and concurrent heat (Sontakke and Salve 2015). All drying methods except freeze drying and osmotic drying uses the application of heat during the drying process by conduction, convection and radiation to force water to vaporises, although removal of water is attain by employing forced air.
A variety of foods and biomaterials are dehydrated in a variety of units under different processing conditions. Energy consumption and quality of dried products are other critical parameters in the selection of a drying process (Sagar and Suresh 2010). Recently, the development of drying technologies drew more attention in the food industry. Foods like fruits contains high moisture content makes them highly susceptible to spoilage of microorganisms such as bacteria and fungi (Rawat 2015).
Dehydration preserves the quality of food in a stable and safe condition by reducing the water activity hence increasing the shelf-life of the product with minimum packaging requirements and decrease in transportation costs (Parikh 2015). Due to the variation of products in the industries, therefore a specific and selected drying method is to be considered to cater for the specific attributes of the product. For an example, heat sensitive foods require special attention during drying to retain the product quality, colour and nutrient content (Parikh 2015). The different type of fruits which have been successfully dried by different drying methods such as drum drying and vacuum oven drying shown in Table 2.4.

Table 2.4 Different fruits dried by drum drying and vacuum oven drying
Drying Methods Fruit References
Drum drying Tamarind (Tamarindus indica L.) Jittanit et al. 2011
Pumpkin (Cucurbita) Vu Thi Thanh Dao 2015
Jackfruit (Artocarpus heterophyllus) Pua et al. 2007 & 2010
Vacuum
oven drying Pineapple pulp (Ananas comosus) Gabas et al. 2007
Mango (Mangifera indica L.) Mahendran 2008
Persimmon pulp (D. kaki) Benedetti et al. 2010
2.2.1Drum Drying
A drum dryer consists of one or two horizontally mounted hollow stainless steel cylinders, a supporting frame, a product feeding system, a scraper and auxiliaries. In operation the drum dryers inner surface are heated up to 200°C. A thin layer (0.5 mm-2 mm) of food product in the form of puree is applied onto the outer drum surface. During the drying period, large amount of thermal energy is released by the transfer from the condensing steam inside the drums to the conducted drum walls to the product (Jurendic and Tripalo 2012). The moisture from the food product is removed at water boiling temperature (Tang et al. 2003). A product may undergo three detailed stages of drying.
The first stage (initial heating period) two horizontally mounted drums dryers rotate about the symmetrical axis. A doctor blade is fitted to the drum at an appropriate location. The wet material is applied to the drum surface and is dried as the heated drum rotates toward the doctor blade due to intensive heat transfer caused by the difference in temperature of the drum surface and wet products. Product temperature increases rapidly to reach the boiling point of free water (Bonaui et al. 1996). Second stage (constant product temperature period) water vaporizes and the thin material changes from liquid to solid state. The drum surface temperature decreases due to evaporate cooling. Third stage (rising product temperature) after removing most of the water, the heat transferred from the steam increases. As a result the increase in temperature of the drum surface (Juming and Guo 2003). The product temperature also gradually increases as drying continues which then scrapes the thin layer of dry material from the drum surface (Pua et al. 2007). Finally, the dry film is scraped off of the cylinder using a blade. The end product would look like a sheet of thin paper.

The drying rate of the thin material layer is determined by the rate of heat transmission from the drum to the product with an assumption that the thin layer of material does not present any restrictions to the vaporizing water. While the product is drying, conduction, radiation and convection simultaneously allows heat flow to product. There are a few factors affecting the heat transfer rate such as the drum wall, water condensed inside the drum and food material adhered to the drum (Ortega-Rivas et al. 2006). There are many types of drum dryer such as single drum dryer and double drum dryer as shown in Figure 1.3 with different variations in their number and configuration of drums, feeding methods, heating system and removal of product. However, a typical drum diameter ranges from 0.5 m to 6 m, 1 m to 6 m in length and a drum wall with thickness between 2 to 4 cm (Juming et al. 2003). Figure 2.4 below describes the single and double drum dryers.

Figure 2.4 Show single and double drum dryers
The drum dryer process is difficult to be controlled due to the complex interactions between all operating variables and parameters (Pua et. al. 2010). Therefore, five types of important parameters need to be controlled to determine the quality of product during the drying process such as steam pressure, rotation speed of drum, drum clearance, pool level between the drums and conditions of the feed material (concentration, physical characteristics, temperature) (Gavrielidou et. al. 2002). Steam pressure and the rotational speed of the drum also influence the product characteristics and capacity of the drum drying operation. Drum drying at low pressure and high drum rotation speed yields a wet product at a low production rate. For example, the production of milk product. The production capacity of dried milk powder can be increased with increased in drum speed and pressure. The drum clearance effect the texture such as thickness and moisture content of a product (Anandharamakrishnan 2017).
The advantages of drum drying include having a high drying rate, the products have good porosity and hence a better rehydration due to boiling evaporation. To add on, drum dryers are easy to operate and maintain. In the food industry, drum dryers have been widely used for a variety of products especially very viscous food products such as pastes but in a small quantity production (Heldman 2003). Liquid and semiliquid food can also be used in drum dryers. In short, many kinds of dried food products such as starch, baby foods, milk powder, fruit and vegetables powder and maltodextrins can be produced (Elmholt et al. 2007).
However, there are certain disadvantages of drum drying method. For instance, high sugar content products will get stick and difficult to be scrapped off from the drum. Products with high salt content also cannot be produced because of potential pitting of drum surface (Heldman 2003). In addition, the high cost of changing the drum surface because of the required precision in the machine serve as a disadvantage (Mohammed et al. 2009). Lastly, the product direct contact of the product with drum surface of a high temperature will make the dried product have undesirable cooked flavours and aromas (Caparino et al. 2012). Table 2.5 describes the different parameters used for drum drying on different fruit samples.
Table 2.5 Different parameters used for drum drying on different fruit samples
Sample used Temperature Pressure Rpm & drum clearance Drying agent References
Tamarind 120 and 140°C – 0.35 rpm and a gap of 0.4 mm. 5.2% MD & 11.8% AG Jittanit et al. 2011
Jackfruit  – 2.3 bar (230 kPa) 1 & 0.01 inch (0.254 mm) 2.65% SL & 10.28% AG Pua et al. 2007
Jackfruit  – 336 kPa 1.2 & 0.01 inch (0.254 mm) & 10 cm pool level 2.65% SL & 10.28% AG Pua et al. 2010
2.2.2Vacuum Oven Drying
Vacuum oven drying is an alternative method to conventional drying because moisture evaporates at lower temperature (Lee and Kim 2009). Vacuum drying is a process in which materials are dried in low pressure environment hence lowering the heat temperature for faster drying (Pere and Rodier 2002). The drying involves two types of phases which are the constant drying period and falling drying period. During drying, liquid is vaporized by heat in a gas state to wet material. Removal of liquid could be free moisture (unbound) or bound within the solid structure. Unbound structure presents as liquid film on the surface of solid particle, easily evaporated off. Bound moisture found between solid particles, must reach the surface to be evaporated off (Parikh 2015).
The transfer of heat occurs through conduction and radiation in vacuum dryers rather than convection a direct heat dryer where a material is directly immersed into a hot gas steam media. During conduction, heat is only transferred to the material as it comes into contact with the dryer’s heated surface (Parikh 2015). Inside the dryer’s heating surface, water flows through and heats the sample to the required temperatures. Unlike other drying methods, the temperature of vacuum drying can be controlled. Drying time are usually long (12-48 hours). A typical drying temperature of vacuum oven dryer of fruits such as mango pulp is at a temperature of 70°C and pressure of 100 kPa (Mahendran 2008). The end products of vacuum oven dried have a puffed structure because moisture and air inside the product expands due to vacuum. Thus, enabling a high heat and mass transfer (Kim 2012). Figure 2.5 describes a vacuum oven dryer.

Figure 2.5 Show a vacuum oven dryer
In vacuum drying, the main transport in moisture migration is pressure driven flow. The three stages in the change of pressure occurs during vacuum drying are firstly, the pressure decreases rapidly depending on the permeability of the material. The second stage, the pressure remains constant. The third stage, the pressure beings to decrease and approaches the reduce pressure in the chamber (Hui 2008). A few factors to be taken into consideration during the drying process such as optimization and selection of the dryer’s parameters and material. The selection includes the dryer’s heating and cooling system, condenser, vacuum-pump and temperature as well as material thickness to produce high quality product (Kim 2012). In addition, during product drying, the product must be placed on a metal shelf to conduct heat efficiently. This is because, the removal of moisture is an endothermic process which causes the decrease in the oven temperature when many samples are dried all together (Nielsen 2014).
Due to the low temperature and fast mass transfer conferred by vacuum drying, therefore it is mainly used in heat-sensitive products to retain the colour, structure, and vitamins of the product (Methakhup et al. 2005). According to Motevali et al. (2011), a major advantage of vacuum drying is its energy conservation, reduced in processing time, air is not present therefore oxidation is inhibited and a high end quality product is obtained. This leads to products having higher retention of nutrients and aroma compounds, when compared to conventional drying (Kim 2012). Certain food materials may developed hard, leathery crusts from high heat exposure therefore by using vacuum drying this can be prevented. According to Parikh (2015) study showed that vacuum dryer, has no occurring of ventilation and the workers working around the dryer is safe. Vacuum dryers are also used to dry toxic and dusty products because of an easier dust recovery principle (Parikh 2015). However, the drawback of vacuum oven drying is that it uses much energy and has an expensive cost of processing (Tsami et al. 1998). Table 2.6 describes the different parameters used for vacuum oven drying on different fruit samples.
Table 2.6 Different parameters used for vacuum oven drying on different fruit samples
Sample used Temperature Pressure Rpm & drum clearance Drying agent References
Pineapple pulp 50°C 26 in Hg
(88 kPa) 48 hours MD : 18kg/100kg of total solid
GA : 18kg/100kg of total solid (dry base- 18%) Gabas et al. 2007
Mango pulp  70°C 1 bar (100 kPa) 24 hours Mahendran 2008
Persimmon pulp 20°C, 30°C, 40°C, and 50°C – 48 hours MD : 18kg/100kg of total solid
GA : 18kg/100kg of total solid (wet base- 18%) Benedetti et al. 2010
2.3MALTODEXTRIN
Maltodextirn (MD) acts as a drying agent to overcome the thermoplasticity and hygroscopicity problems occurring in drying fruit juices with high sugar content (Domingo et al. 2017). Maltodextrin consists of b-D-glucose units linked mainly by glycosidic bonds and usually classified according to their dextrose equivalency (DE). The DE of a maltodextrin value measures the amount of reducing sugars present, expressed as a percentage of the total dry substance (McArdle and Hamill 2011). Maltodextrin helps in reduction of stickiness, agglomeration problems during storage for both drying methods hence improving product stability (Jittanit et al. 2011).
2.4PHYSICOCHEMICAL ANALYSIS
2.4.1Colour Analysis
Colour is defined as the sensation that an individual experience when radiant energy within the visible spectrum (380–700 nm) falls upon the retina of the eye (Nielsen 2014). Colour is one of the most important characteristics in a food product because it makes the food looks more attractive and visually appealing. The colour also sets people’s thinking and expectation regarding the likely of the flavour and taste of the food for example, the ripeness of a fruit can be determined based on its colour (Pathare et al. 2013). Consumers also make assumptions in which a more intensely coloured foods and drinks will have a more intense flavour or taste as well when laboratory research are conducted and the results obtained from the consumers are same as mention earlier (Spence 2015).
Although, humans are capable of detecting a variety of colours by their naked eyes but the colours maybe inaccurately interpreted. Therefore, objective colour-ordering systems and colour spaces have been developed to measure the colour of food products (Nielsen 2014). The HunterLab system which is a colour-measuring system was introduced by Richard S. Hunter that was first published in 1942 to replace the CIE (Commission Internationale de l’Eclairage). In the food industry, the HunterLab system is widely used for colour measurement of food (Nielsen 2014). The addition of colour to food may come in various form such as natural colouring and artificial colouring. Colours are added to impart the food colour hence to also stimulate the appetite (Sharma 2014).
2.4.2Moisture Content
Moisture content is a measure of the amount of water present within the sample which described in percentage. Determination of moisture content also is necessary to calculate the content of other food constituents on a uniform basis (Nielsen 2014). It can be expressed into two forms wet basis or dry basis. The wet basis moisture content is the amount of water per unit mass of wet sample while dry basis moisture content is the amount of water per unit mass of dry solids in a sample (Iglesias and Chirife 2012). There are two categorise to measure moisture content which are the direct and indirect methods (Nielsen 2014). The direct method is by drying and distillation which remove water using different methods. However, for indirect method it determined moisture content based on the properties of the food that relates to the present of water such as density, freezing point and specific gravity. Moisture is a variable factor because it is highly dependent on the changes in temperature and climate. Moisture content in food powders usually varies in a broad range from 1-5% for milk powder, 3-5% for dried tea
powders to 10-15% for commercially available flours (Opalinski et al. 2016). A desirable moisture content in a food however should be lesser than 15% to ensure the food are stable to both microbial and chemical degradation of food powder (Jagtiani et al. 2014). Physcial properties of a food can also be affected by moisture content such as weight, density, reflective index and others (Serrano et al. 2011).
2.4.3Water Activity
Water activity (aw) can be described as the ratio of the partial vapour pressure of water in a substance to the partial vapour pressure of water in a standard state under the same temperature (Food and Drug Administration 2015). The determination of water activity is determine based on the unbound or least tightly bound quantity of water in the sample (Nollet 2004). Water molecules in food which are unbound to food molecules also known as free water tends to encourage the growth of unfavourable organisms such as yeasts, bacteria and molds (fungi) (Nielsen et al. 2012). Therefore, decreased in water activity prevents the microbial growth. Dried foods with water activity between 0.2 and 0.5 ensure a stable product that prevents physical and chemical changes such as browning reaction and lipid oxidation (Dirim and Caliskan 2012). Fungi is inhibited at water activity less than 0.7, whereas bacteria is inhibited at water activity less than 0.9 (Troller and Christian 2012). In the FDA (2015) guides, water activity should be controlled to 0.85 or less in the finished products such as food powders like milk powder commonly have a water activity level of 0.70.
2.4.4Hygroscopicity
Hygroscopicity is defined as the capability of a substance to absorb water or moisture from the surroundings. Absorption of water vapour from the environment by molecules of the substance often leads in a physical change of the substance (Zhang et al. 2012). Hygroscopicity usually occurs at room temperature. Most hygroscopic materials are salts, but many other materials display the same property such as zinc chloride, sodium hydroxide crystals, nylon and honey (Suhag and Nanda 2016). Dried food products having a hygroscopicity more than 25% is highly hygroscopic. High percentage of hygroscopicity can be caused by the particle size. A product having smaller particles have a bigger contact surface thus having a higher number of active sites. A higher number of active sites will increase in hygroscopicity due to higher water absorption (Ribeiro et al. 2016). Therefore, high hygroscopic products requires drying aids such as maltodextrin to decrease hygroscopicity problems (Costa et al. 2014).
2.4.5Degree of Caking
Caking is an undesirable transformation of bulk powders which is a common problem a few industries such as food, fertilizer, detergent and pharmaceutical. Powder caking is defined as the damaging aggregation of particles, that turns a free flowing powder into a consistent solid (Mathlouthi and Roge 2003). The quantity of caked materials can vary from large lumps that breaks up when stressed, hence no longer returns to the representative original state of material due to the irreversible fusion of particle. There are two factors that contributes the transformation of bulk powders such as the environment and mechanical conditions of a material. Certainly, caking is a disadvantage factor to a food material that leads to the decrease of functionality and quality of the product (Zafar et al. 2017). Prevention of caking can be overcome by using anticaking agents such as the stearates of calcium, magnesium and silicon dioxide. Anticaking agents are able to delay and prevent the caking of powder (Lipasek et al. 2011).
2.4.6Wettability
Wettability is the tendency of one fluid to spread on or adhere to a solid surface in the presence of other immiscible fluids. In other words wettability is where the actual process by which a liquid substance spreads on (wets) a solid substrate or surface (Shabib et al. 2015). The moisture content of the powder also affects wettability. A lower moisture content in the powder takes a longer time to wet the powder (Phisut 2012). Apart from that, wettability of a product depends on the amount agglomerates such as free fats present on the surface of the product reduces wettability therefore carrier agents such as maltodextrin is used to improve the wettability of product (Nurhadi et al. 2012). The simplest method to study on wettability is by measuring the time taken for the powder to sink together often have a better wettability characteristics (Chen and Mujumdar 2008). There are no specific requirements on wettability, however powders having a wettability index between 30-60 seconds is considered a wettable powder (Schuck et al. 2012).
2.4.7Flowability
Powder flow can be described as the relative movement of a bulk of particles along the container wall surface (Jan et al. 2016). In lab and production setup, workers identify that powder flow is complex. The flow of the powder’s behaviour is multi-dimensional and also depend on the powder characteristics. The factors that tends to affect flowability are both the material (powder) physical characteristics and the equipment used upon handling and processing the material (Mendez et al. 2010). Examples of certain powder characteristics such as particle size, moisture content, bulk density, wall friction, permeability and cohesive strength affects the flowability rate also known as flow properties (Begum et al. 2017). A collective forces that acts on individual particles such as electrostatic force, cohesion, adhesion and friction in which results in the formation of flow properties (Jan et al. 2016).
2.4.8Water Solubility Index (WSI)
The property of a solute in solid, liquid or gaseous chemical substance to disassociate in a solvent such as a solid, liquid or gaseous solvent to form a solution is known as solubility. It is defined as the reconstitution property which used to determine the effect of process parameters (Santhalakshmy et al. 2015). The physical and chemical properties of the type of solute and solvent used affects the solubility of a food product. One of the main benefit of the properties of a powder product is the capability of it dissolving instantly in water. Therefore, a good quality powder that has a good water solubility index can be produced by the addition of drying agents such as maltodextrin. (Vidovic et al. 2014). Other factors that influence the solubility also includes the temperature, pH of the solution, operating conditions such as speed and agitation (Schuck et al. 2012).
2.5RECONSTITUTION ANALYSIS
Reconstitution of powder is defined as the ability of the powder to completely wet, sinks, disperses and dissolves without clumping together (Koc et al. 2012). Wettability is where the actual process by which a liquid substance wets a solid surface. Sinking of the powder particles below the liquid surface is known as sinkability. Dispersion of particles is known as dispersibility with the aid of little stirring hence dissolving the soluble particles of powder in the liquid. All the mechanisms above, are nearly related to the particle size, density, surface area and porosity (Kwapinska and Zbicinski 2005). The overall reconstitution properties are influence by the conditions of drying operations such as drying temperature and also the last step of reconstitution of powder which is dissolving plays a significant role in the overall reconstitution quality (Hogekamp and Schubert 2003).
2.5.1Beta Carotene Content
The carotenoids are natural pigments and most important class of pigments that are found in plants, algae and photosynthetic bacteria that gives the vibrant yellow, orange and red colour in it (Rajauria and Tiwari 2017). Carotenoids defines the quality parameters of fruit and vegetables (Eldahshan and Singab 2013). Carotenoids also plays an important part in human health such as reducing the risk of cancer, cardiovascular diseases, muscular disease and immune disorders, hence a diet with sufficient amount of carotenoids to lead a healthy lifestyle (Krinsky and Johnson 2005).
There are two different groups of carotenoids which are ?-carotene, ?-carotene as well lycopene and xanthophylls (?-crypotoxanthin, zeaxanthin and lutein) (Higdon 2004). ?-carotene is a type of pro-vitamin which the body converts to vitamin A. Vitamin A found in conventional food and dietary supplements are an effective source of vitamin A from ?-carotene compared to others (Eldahshan and Singab 2013). The beta carotene content among the fruits of ambarella, Bintangor orange and Sarawak pineapple are with values of 205.0 µg, 155.0 µg and 270.0 µg. According to Ministry of Health Malaysia (1997), pineapple has the highest beta carotene content.

2.5.2Vitamin C Content
Vitamin C is also known as ascorbic acid which is the most important vitamin to the human body and are naturally present in fruits and vegetables. Vitamin C is an organic compound consisting of carbon, oxygen and hydrogen Ascorbic acid plays its role mainly as protective metabolite in fruits and vegetables (Kim 2012). Ascorbic acid includes all compounds which exhibits the biological activity such as oxidation and ester form (Fatin and Azrina 2017). L-ascorbic acid (AA) being the main biologically active form of vitamin C, which then oxidizes to L-dehydroascorbic acid (DHA) being less biologically active form (Fenoll et al. 2011). Factors that causes the oxidation of vitamin C are pH, temperature, light and presence of oxygen (Fatin and Azrina 2017). Common fruits mainly citrus fruits like lemons, melons, pineapple, oranges and strawberry (Hernandez et al. 2006). The vitamin C content among the fruits of ambarella, Bintangor orange and Sarawak pineapple are with values of 36.0 mg, 26.7 mg and 47.80 mg. According to the US Food and Drug Administration, USDA (2016) pineapple has the highest vitamin C content.
AA and DHA are easily prone to oxidation especially at high pH therefore, during determination of ascorbic acid needs to be done in a low pH environment (Nielsen 2014). There are many methods available to determine vitamin C such as titration, spectrophotometer and high performance liquid chromatography (HPLC). (Spinola et al. 2012). However, oxidation-reduction titration method are commonly used for the determination of vitamin C in fruits in which ascorbic acid (AA) is oxidized to dehydroascorbic acid (DHA). The visual endpoint of titration is easily identified when a rose pink colour is formed in the acid solution (Fatin and Azrina 2017).

Chapter III
MATERIAL AND METHOD
3.1MATERIALS
3.1.1Preparation of Fruit Samples
The fruits used in this study were ambarella, Bintangor orange and Sarawak pineapple were purchased respectively from wet markets and supermarkets in Kuala Lumpur and Sarawak, Malaysia. They were purchased in three different batches. The fruits selected had minimal defects and were uniform in terms of maturity, size, colour and hardness. Before cutting the fruits, they were washed thoroughly under running water to remove any chemical residue and physical hazards such as pesticides, slime and dirt.
After washing, each fruit was peeled, deseeded, with any defects on the pulp trimmed off, sliced into small pieces then weight using an electronic balance respectively. There were approximately 600-800 g of pulps for each fruit. Ambarella, Bintangor orange and Sarawak pineapple were then vacuum-sealed and kept in the freezer at -20°C before the fruits are subjected to further processing and analysis.
3.1.2Chemicals and Reagents
All chemicals and reagents used in this experiment are listed in Appendix A.

3.1.3Apparatus and Equipment
All apparatus and equipment used in this experiment are listed in Appendix B.

3.2PREPARATION OF SAMPLES AND DRYING PROCESS
3.2.1Preparation of Fruit Puree
To prepare the fruit puree, the vacuum-packed fruit pulps were taken out from the freezer and thawed for 30 minutes. After thawing, the fruit pulps were blended with maltodextrin for 30 seconds at low speed and 1-4 minutes at high speed using the food processor machine (Pua et. al. 2010). Then, fruit purees were formed Figure 3.1.
In a preliminary study, different percentage such as 10%, 15%, 20% and 50% (v/w) of maltodextrin were tried and incorporated into the drying process. Finally 50% (v/w) was chosen due to better end product quality with a higher yield amount. Commercial maltodextrin was used and incorporated into purees for reduction of stickiness for both drying methods. Amount incorporated into fruit pulps were 50% (v/w) for both drying methods. For example, 0.5 kg of maltodextrin was blended with 1 kg of fruit in a food processor machine until the maltodextrin completely dissolved (Jaya and Das 2004).

Figure 3.1 Purees of ambarella (left), Bintangor orange (middle), and Sarawak pineapple (right) incorporated with 50% (v/w) maltodextrin
3.2.2Drum Drying
The drum dryer was warmed up for a minimum of 40 minutes each time before carrying out the drying process. The warming out process was done to ensure smooth and more efficient drying process could be carried out, during which the dried fruit will not stick on the surface of the drum (Pua et al. 2010). Prepared fruit purees of approximately 1.5 cm thick were applied continuously on the heated double drum dryer (R.Simon (Dryers) Ltd. Nottingham England, Universal Test Machine) Figure 3.2 at 0.02 mm drum clearance and 10 cm pool level. The drum rotation speed was set at 2 rpm with a steam pressure set at 3 bars and the temperature ranged from 130°C to 140°C.
As the drum dryer continuously rotates, the heat from inside the drum heats the body of the drum dryer hence dries the puree on the outside of the drum dryer. The dried material was removed as flakes from the drum surface using doctor blades. Dried flakes were immediately collected and grinded into powder form using a grinder and stored in an airtight condition through vacuum packaging for further observation and analysis (Pua et al. 2010).

Figure 3.2 Drum dryer
3.2.3Vacuum Oven Drying
Before drying, the vacuum oven is switched on by warming up the pumps for at least 1 hour to ensure the pump is working systematically. Besides that, system pull down test was also performed to detect if there were any leakage present in the hoses and pipes by pulling on all the hoses and pipes of the system (Miller et al. 2013). Fruit purees of approximately 1.5 cm thick were poured into aluminium foil, put on a stainless-steel baking tray. Then the tray was placed into the vacuum dryer operated at a temperature of 70°C and pressure of 1 bar for 24 hours under vacuum condition (Benedetti et al. 2010). Dried flakes were immediately collected and grinded into powder form using an ordinary American brand grinder and stored in an airtight condition through vacuum packaging for further observation and analysis.

Figure 3.3 Vacuum oven dryer
3.3PROCESS YIELD
The process yield was determined according to Pua et al. (2010). The process yields of drum dried and vacuum oven dried powder were calculated after the drying process using the following equation:
Equation (3.1):
Process yield (%) = Weight of drum dried or vacuum oven dried fruit powder (g)Weight of fruit purees g x 100%
3.4PHYSICOCHEMICAL ANALYSIS OF POWDER
Each and every drum dried and vacuum oven dried ambarella, Bintangor orange and Sarawak pineapple powder were subjected to all analysis which comprised of colour, moisture content, water activity, degree of caking, hygroscopicity, wettability, flowability, water solubility index, vitamin C content analysis, beta-carotene content analysis and reconstitution analysis.
3.4.1Colour Analysis
The colour of fruit powder was determined using Hunter-Lab ColorFlex EZ Colorimeter Figure 3.4. The equipment was connected to a computer with EasyMatch QV-ER software for result recording purposes. Before each sample analysis, the calorimeter was standardized with a black ceramic tile followed by a white ceramic tile. After calibration, the powder was filled into a quartz sample cup to about 2/3 and placed onto the sample port then the quartz sample cup was covered with an opaque cup around it ready for sample measurement. The samples were scanned at three different locations by rotating the sample cup at 90° to obtain an average reading for each sample. The colour reading was expressed in terms of L* for degree of lightness or darkness, a* for degree of redness or greenness, and b* for degree of yellowness or blueness (Pua et al. 2010).

Figure 3.4 Hunter-Lab ColorFlex EZ colorimeter
3.4.2Moisture Content
Moisture content of fruit powder was determined according to Fridh et al. (2014) with some modifications by using the Mettler Toledo halogen moisture analyser Figure 3.5. First, clean the sample plate and sample plate holder then place the sample plate into the sample holder. Both the sample holder and sample plate were placed in the balance then tare the balance. Approximately about 5 g of powder were weighed and spread evenly on the sample plate. The initial weight of the sample was recorded and dried in the moisture balance at 105oC for 15 minutes. The cover of the moisture balance is then covered to start the drying process. The unit’s display panel on the moisture balance continuously updates the statues of the drying process. The analysis automatically ends when the drying process is complete. After drying, the final weight of powder was recorded. Moisture content can be calculated by using the following equation:
Equation (3.2):
Moisture content (%) = Weight of wet sample g- Weight of dry sample (g)Weight of wet sample g x 100%

Figure 3.5 Mettler Toledo halogen moisture analyser
3.4.3Water Activity
Water activity of fruit powder was determined by using AquaLab Pre Water Activity Meter Figure 3.6. The water activity meter is warmed up for an hour before measurement could be taken to obtain a more accurate and uniform reading. Then approximately 2/3 of powder were filled into cleaned sample cups and placed into the designated compartment of the water activity meter for measurement. The end of a measurement was indicated by a beeping sound and the reading was recorded (Silva et al. 2016).

Figure 3.6 AquaLab Pre water activity meter
3.4.4Hygroscopicity
Hygroscopicity of fruit powder was determined according to Zungur et al. (2016) with some modifications. About 1 g of powder was weighed and spread evenly in a pre-weighed 100 mL beaker. The beaker was placed in a desiccator with its bottom part pre-filled with saturated sodium chloride solution providing 75.3% relative humidity at 25°C. The powder were weighed and recorded after one week of storage.
Hygroscopicity was calculated by using the following equation:
Equation (3.3):
Hygroscopicity = Final weight of sample after one week g- Initial weight of sample (g)Initial weight of sample g x 100%

Figure 3.7 Desiccator with its bottom part pre-filled with saturated sodium chloride solution
3.4.5Degree of Caking
Degree of caking of fruit powder was determined according to Koc et al. (2012) with some modifications. About 5 g of dried fruit powder were weighed and sieved through a 500 ?m sieve. The powder was shaken constantly for one minute during the sieving process and then the weight of powder remained on the sieve was recorded. Degree of caking was calculated by using equation below:
Equation (3.4):
Degree of caking (%) = Final weight of sample g- Initial weight of sample (g)Initial weight of sample g x 100%
3.4.6Wettability
The wettability of fruit powder was determined according to Gong et al. (2008) with some modifications. About 1 g of powder was weighed and dissolved into 100 mL of distilled water at 25°C in 250 mL beaker. The wetting time is the time required for the powder to be wetted was recorded using a stopwatch.
3.4.7Flowability
Flowability of fruit powder was determined according to Campos and Ferreira (2013) with some modifications. Firstly, a funnel was set 2 cm above the flat base. About 5 g of powder were weighed and poured through the funnel carefully. The powder’s heap was formed at the base. Then, the diameter of the powder’s heap formed was recorded. Angle of repose-represented flowability was calculated by using equation
Equation (3.5):
Angle of repose/ Flowability (°) = tan-1Height of funnel from base cmRadius of sample on base cm x 100%
3.4.8Water Solubility Index (WSI)
The water solubility index of fruit powder was determined by dissolving 1 g of weighed powder into a centrifuge tube containing 10 mL of distilled water. The suspension was vortex for 1 minute and placed into a water bath at temperature of 37oC for 30 minutes, with shaker to fully dissolve the solution. After that, the centrifuge tube was centrifuged at 4400 rpm for 10 minutes to collect the supernatant. The supernatant was poured into a pre-weighed aluminium cup and put to dry in a convection oven at 105°C and weighed after 5 hours (Silva et al. 2009). WSI was calculated by using the following equation:
Equation (3.6):
Water solubility index, WSI (%) = Weight of dried supernatant (g)Initial weight of sample g x 100%
3.4.9Total Colour Change (?E)
The colour change between fresh fruit puree samples and fruit powder were determined according to Mohammadi et al. (2008) using Hunter-Lab ColorFlex EZ Colorimeter. The total colour change (?E*) between fresh fruit puree samples and dried fruit powder was calculated using the equation in the next page:
Equation (3.7):
Total colour change, ?E* = (Lo* -L*)2+(ao* -a*)2+(bo* -b*)2Where Lo*, ao* and bo* are the colour representing the fresh fruit purees while L*, a* and b* representing the values of fruit powder.
3.5RECONSTITUTION ANALYSIS OF POWDER
The reconstitution of fruit powder was carried out by rehydrating the powder with water. Firstly, 2 g of powder was weighed and added to 50 mL of distilled water at 26°C in a 250 mL beaker. A magnetic stirrer and a magnetic stirring bar with a size of 3 mm x 7 mm were used to ensure the mixture fully dissolves (Goula and Adamopoulos 2009).
3.5.1Total Colour Change (?E)
The colour change between fresh fruit puree samples and reconstituted fruit powder were determined as mentioned in subtopic 3.4.9. The total colour change (?E*) between fresh fruit puree samples and reconstituted dried fruit powder was calculated using the equation below:
Equation (3.8):
Total colour change, ?E* = (Lo* -L*)2+(ao* -a*)2+(bo* -b*)2Where Lo*, ao* and bo* are the colour representing the fresh fruit purees while L*, a* and b* representing the values of reconstituted fruit powder.
3.5.2Beta Carotene Content
a)Preparation of Standard Solution and Standard Curve
The standard curve of ?-carotene was prepared according to Ren and Zhang (2008) with some modifications. About 0.01 g of commercial ?-carotene powder were dissolved into 10 mL acetone to make the stock solution with a concentration of 1 mg/mL. Different concentrations of working solutions of 5 ?g/mL, 10 ?g/mL, 15 ?g/mL, 20 ?g/mL and 25 ?g/mL were then prepared by diluting the stock solution with different volumes of acetone. Volume of acetone required to prepare different concentrations of working solution was calculated using equation the below:
Equation (3.9):
M1V1 = M2V2
Where,
M1 = Concentration of stock solution (1 mg/mL)
V1 = Volume of stock solution used to prepare working solution
M2 = Concentration of working solution
V2 = Volume of working solution
b)Beta Carotene Content Analysis
The beta carotene of analysis of powder was done according to Scrob et al. (2014) with some modifications. About 3 g of powder were weighed and dissolved with 10 mL of distilled water. The solution was allowed to stand for 30 minutes and were incubated at 25°C. After that, 20 mL of cold acetone which was refrigerated overnight was added to sample solution and sample was again incubated at 25°C for 15 minutes to form a paste. Then the sample solution had undergone vacuum filtration with vacuum pump, filter paper, side-arm conical flask and Büchner funnel. Residues on the Büchner funnel were transferred to a mortar and added with acetone for further extraction of carotenoids. The used filter papers was overlap with new filter papers to ensure smooth process of filtration takes place for the next filtration. These procedures of extraction and filtration were repeated 3 times to extract more carotenoids.
After the filtration process, 50 mL of petroleum ether was poured to the filtrate in a separatory funnel. Two separate layers were formed. The bottom layer was discarded and the upper layer was collected and filtered with 15 g of sodium sulphate anhydrous to remove excess of water. Later, the filtrate was transferred to a round bottom flask. A rotary evaporator was used to evaporate off the petroleum ether in the filtrate at 35°C. The evaporated extract was reconstituted with 1 mL of cold acetone. The total carotenoid content present in the extract was measured at wavelength of 450 nm using a UV-visible spectrophotometer. The concentration of beta carotene of dried fruit powder were determine by referring to the pre-prepared standard curve as a reference.

3.5.3Vitamin C Content
a)Preparation and Standardization of Iodine Solution
Standardization of iodine solution was prepared according to Suntornsuk et al. (2002) with some modifications. 2 g of pre-weighed potassium iodide and 1.3 g of pre-weighed iodine was placed into a 250 mL beaker. Then, distilled water is added into the beaker and swirled for a few minutes until the iodine completely dissolved. After that, the iodine solution was transferred to a volumetric flask and distilled water is used to make up the solution to the 1 L mark on the volumetric flask.
b)Preparation of Starch Indicator Solution
About 0.25 g of soluble starch was weighed and added into a 50 mL of near boiling water in a 100 mL conical flask. The solution was stirred until the starch completely dissolved and then was allowed to cool before use (Suntornsuk et al. 2002).
c)Vitamin C Content Analysis
The vitamin C content in the dried fruit powder and fresh fruit purees were determined according to Elgailani et al. (2017) with some modifications. First, 5 g of powder was weighed into a 250 mL conical flask. Then, 150 mL of distilled water and 1 mL of starch indicator solution is added. The sample is titrated with standardized iodine solution. A permanent dark blue coloured solution obtained indicates the endpoint of a titration. The titration was repeated 3 times to obtain an average result for each sample. The amount of vitamin C in dried fruit samples and fresh fruit purees was calculated using the equation in the next page:
Equation (3.10):
M1V1n1= M2V2n2Where,
M = molar of KIO3
V = Final volume in the conical flask before dilution (mL)
n = no of moles of the equation, 1 mole of iodine equals to 3 mole of ascorbic acid
3.6STATISTICAL ANALYSIS
The analysis of physicochemical properties, reconstituted properties, beta carotene and vitamin C content of drum dried and vacuum oven dried ambarella, Bintangor orange and Sarawak pineapple powder were done in triplicate (n=3) to obtained an average result. IBM SPSS 22 software is used to conduct the statistical analysis. Independent sample t-test was carried out to determine the significant differences (p<0.05) among the average results obtained.

Chapter IV
RESULT AND DISCUSSION
4.1PROCESS YIELD
The process yield corresponds to the product recovery and is mainly determined by the type of dryer and the drying agent used (Nurhadi et al. 2012). In the industry, the process yield of a product is an important parameter in determining success of the product, which is also closely related to the production cost and efficiency invested. Process yield is defined as the weight of the powder collected over the weight of total solids in the feed (Deshmukh et al. 2017). Figure 4.1, shown the ambarella, Bintangor orange and Sarawak pineapple powder that were successfully produced using drum drying and vacuum oven drying methods. The process yield of dried powder of ambarella, Bintangor orange and Sarawak pineapple using drum drying and vacuum oven drying were shown in the Table 4.1.

9906007620A
00A
21240758255B
00B
3248025-1270C
00C

1019175-635D
00D
2143125-635E
00E
3248025-635F
00F

Figure 4.1 (a) Drum dried ambarella; (b) Drum dried Bintangor orange; (c) Drum dried Sarawak pineapple; (d) Vacuum oven dried ambarella; (e) Vacuum oven dried Bintangor orange; (f) Vacuum oven dried Sarawak pineapple
Table 4.1 Process yield of drum dried and vacuum oven dried of ambarella, Bintangor orange and Sarawak pineapple powder
Drum drying (%) Vacuum oven drying (%)
Ambarella 20.79±2.09b 36.51±0.72a
Bintangor orange 31.13±2.76b 43.27±0.94a
Sarawak pineapple 21.21±1.59b 38.80±0.47a
Data expressed in mean ± standard deviation based on triplicate readings (n=3). a-b Values in each row with different superscripts are significantly different at (p<0.05)
According to Table 4.1, the process yield of drum dried ambarella, Bintangor orange and Sarawak pineapple powder were lower by 15.72%, 14.14% and 17.59% compared to vacuum oven dried powder of ambarella, Bintangor orange and Sarawak pineapple. This can be attributed due to the stickiness of the product adhering to the drying chamber while drying (Nurhadi et al. 2012). The stickiness in the fruits is due to the presence of two molecular weight sugars namely glucose and fructose as well as some organic acids (Caparino et al. 2012). The hygroscopic nature and low glass transition temperature of the glucose and fructose in the fruits lead to the dried fruits becoming sticky hence making it hard to be scraped out from the drum surface (Muzaffar et al. 2015). The lower yield was caused by the decrease in the rotation speed of the drum dryer caused by the fruits’ sticky properties (Chia and Chong 2015).
4.2PHYSICOCHEMICAL ANALYSIS OF POWDER
Physicochemical properties play a critical role in the product improvement because consumers pick and devour products according to the appearance, texture and flavour. Generally the physical and chemical properties of fruit powder impacts the production of fruit powders in the market (Saifullah et al. 2016). The physical characteristics measured in this experiment are colour, moisture content, water activity, degree of caking, hygroscopicity, wettability, flowability and water solubility index (WSI) while the chemical characteristics liable to be influenced such as total colour change, vitamin C content and beta carotene content were also tested in this experiment. The results of the physicochemical analyses were recorded in the tables as follow.

4.2.1Colour Analysis
Colour is an important parameter as it is the first physical characteristic that attracts consumers to consume the food. It may also show changes in food quality due to processing, handling and storage (Roongruangsri and Bronlund 2016). The colour of food is usually measured in L*, a*, and b* as stated in the HunterLab system in which higher L* values indicates lightness (100) while lower L* values indicates darkness (0), positive a* values indicates the colour is close to redness (0 to 60) while negative a* values indicates the colour is close to greenness (0 to -60) and positive b* values indicates the colour is close to yellowness (0 to 60) while negative b* values indicates the colour is close to blueness (0 to -60) (Caparino et al. 2012). The parameters L*, a* and b* values of puree for ambarella were 46.20±2.20, -4.96±0.20 and 12.87±2.74, for Bintangor orange were 54.05±1.18, 17.27±1.90 and 56.43±1.30 while, for Sarawak pineapple were 73.49±1.20, -1.91±0.72 and 30.16±3.46. Table 4.2 illustrates the colour of dried powders of ambarella, Bintangor orange and Sarawak pineapple were different from the puree samples by using drum drying and vacuum oven drying.

As shown in Table 4.2, both drum dried and vacuum oven dried powder of ambarella and Bintangor orange of the L* values had no significant difference at (p; 0.05) however, vacuum oven dried powder of Sarawak pineapple had a higher L* value of 89.60 compared to drum dried powder with a value of 85.96. Therefore, the powder produced by vacuum oven drying was able to maintain its lighter colour because of the lower processing temperature used however turns darker during drum drying. The lightness in the powder colour could also be due to the addition of carrier agent such as maltodextrin (Fegus et al. 2015). This result may be explained by the fact that vacuum oven drying is more likely to have fewer changes in the colour of the final products. The condition of vacuum oven drying influenced by the temperature on product lightness (Michalska et al. 2016). During drum drying, higher processing temperatures were used thus darker fruit powder were produced due to non-enzymatic browning such as Maillard reaction and caramelization of the sugar in the fruits (Patel et al. 2013).

Table 4.2 The colour of drum dried and vacuum oven dried of ambarella, Bintangor orange and Sarawak pineapple powder
Ambarella Bintangor orange Sarawak pineapple
L* a* b* L* a* b* L* a* b*
Drum drying 83.68±0.61a 3.39±0.11a 24.57±0.60a 79.54±1.06a 6.82±0.16b 30.79±0.98b 85.96±0.82b 0.37±0.03a 12.37±2.25b
Vacuum
oven drying 84.41±3.41a 1.11±0.06b 22.57±1.85a 79.72±2.87a 8.90±0.06a 38.07±2.50a 89.60±1.02a 0.24±0.03b 19.80±0.85a
Data expressed in mean ± standard deviation based on triplicate readings (n=3). a-b Values in each column with different superscripts are significantly different at (p;0.05). Abbreviation: L* represents lightness and darkness, a* represents greenness and redness, b* represents blueness and yellowness
The vacuum oven dried ambarella and Sarawak pineapple powder showed a lower a* values which were 1.11 and 0.24 indicating the powder were more greenish in colour compared to drum dried ambarella and Sarawak pineapple powder which were 3.39 and 0.37. However, vacuum oven dried Bintangor orange had a higher a* value which was 8.90 indicating the powder was more reddish in colour compared to drum dried Bintangor orange powder which was 6.82. Devitt et al. (2010) found that that low processing temperature is able to retain the high pigment contents in the fruit such as beta carotene. However, a* values of for both drum dried and vacuum oven dried Sarawak Pineapple powder were low. A possible explanation for this might be due to the addition of the carrier agent such as maltodextrin (Fegus et al. 2015).

Both drum dried and vacuum oven dried ambarella powder of the b* values had no significant difference at (p; 0.05). As shown in Table 4.2, vacuum oven dried Bintangor orange and Sarawak pineapple powders have higher b* values which were 38.07 and 19.80 compared to drum dried powders of Bintangor orange and Sarawak pineapple which were 30.79 and 12.37. This can be caused by the lower processing temperature used, and both the fruits contained higher carotenoid pigments, which enabled it to retain the carotenoid pigments that contributed to the yellowish colour of the fruit such as lutein and xanthin (Faria et al. 2009).
Moisture Content
One of the major components which make up about 80% of most food products is water (Karam et al. 2016). Presence of high moisture in food allows microbial growth such as yeast, bacteria and mould to spoil it (Saifullah et al. 2016). The high moisture content also decreases the shelf life and reduces the food quality. One of the oldest, common and cheapest preservation technique of reducing the moisture in food is drying. The application of drying is able to extend the shelf life of food by preserving the food for about six months (Kutz 2012). Drying of food helps to improve the quality as well as delay the process of microbial and chemical deterioration in food (Thirugnanasambandham and Sivakumar 2015). High moisture in food powder tend to have increment of cohesiveness due to the inter-particle liquid bridges. This inter-particle liquid bridges is in charge of unconstrained agglomeration of particles which results in extreme caking issues (Karam et al. 2016). Table 4.3 shows the moisture content of drum dried and vacuum oven dried ambarella, Bintangor orange and Sarawak pineapple powder.
Table 4.3 Moisture content of drum dried and vacuum oven dried of ambarella, Bintangor orange and Sarawak pineapple powder
Drum drying (%) Vacuum oven drying (%)
Ambarella 4.17±0.16b 5.59±0.62a
Bintangor orange 4.57±0.21b 5.54±0.18a
Sarawak pineapple 4.35±0.12b 5.39±0.32a
Data expressed in mean ± standard deviation based on triplicate readings (n=3). a-b Values in each row with different superscripts are significantly different at (p;0.05)
As shown in Table 4.3, the moisture content of vacuum oven dried powder of ambarella, Bintangor orange and Sarawak pineapple were higher 1.42%, 0.97% and 1.04% than the drum dried powder of ambarella, Bintangor orange and Sarawak pineapple respectively. The moisture content value of vacuum oven dried powder were similar to the values acquired in the study of vacuum oven dried pineapple powder by Nowicka et al. (2015) in which pineapple powder had moisture content of 5%. Comparison of the findings with those of other studies confirms the moisture content values of drum dried powder were similar to the values acquired in the study of drum dried tamarind powder by Jittanit et al. (2011) in which the tamarind powder had moisture content between 3.46% to 4.41%.
The changes in the moisture content value of the drum dried and vacuum oven dried powder can be caused by the different temperatures used in drying and the rotation speed of the drum dryers. The higher processing temperature used in drum drying compared to vacuum oven drying aids water to evaporate faster from the food powder surface (Pua et al. 2007). When the rotation speed of drum dryer increases, the moisture content of drum dried powder also increases because the residence time of the feed on the drum surface reduces (Pua et al. 2010).
Water Activity
The determination of water activity is an important parameter in food products. It reflects the stability of food products in respect to microbial growth, physical properties, chemical and enzymatic reactions (Venir and Maltini 2013). The scale of water activity begins from 0 to 1.0 in which 0 being bone dry and 1.0 being pure water (Fellows 2000). Both water activity and glass transition is a desirable factor to evaluate the product stability. A product will achieve the greatest stability when it is at the monolayer moisture content, with a water activity value of 0.1-0.3 or when it is at, or below glass transition temperature which is 100oC (Sablani et al. 2007). Table 4.4 describes the water activity of drum dried and vacuum oven dried ambarella, Bintangor orange and Sarawak pineapple powder.

Table 4.4 Water activity of drum dried and vacuum oven dried of ambarella, Bintangor orange and Sarawak pineapple powder
Drum drying Vacuum oven drying
Ambarella 0.307±0.01b 0.376±0.02a
Bintangor orange 0.343±0.02b 0.489±0.01a
Sarawak pineapple 0.377±0.02b 0.445±0.03a
Data expressed in mean ± standard deviation based on triplicate readings (n=3). a-b Values in each row with different superscripts are significantly different at (p;0.05)
Based on Table 4.4, the vacuum oven dried powder of ambarella, Bintangor orange and Sarawak pineapple had water activity of 0.376, 0.489 and 0.445 were higher compared to drum dried powder of ambarella, Bintangor orange and Sarawak pineapple which had water activity of 0.307, 0.343 and 0.377 respectively. The water activity of vacuum oven dried powder were similar to the values acquired in study of vacuum oven dried powder from Jaya and Das (2009) in which mango powder had water activity of 0.44 and pineapple powder had water activity of 0.41. This study supports evidence from previous observations that drum dried powders had similar values of water activity to the drum dried tamarind powder, which is 0.326 (Jittanit et al. 2011).
Food spoilage caused by microbial activity is inhibited below water activity 0.6, whereas bacteria are inhibited at less than 0.9 and fungi are inhibited at less than 0.7 (Troller and Christian 2012). However, dried foods with water activity between 0.2 and 0.5 ensure a stable product without signs of any physical and chemical changes (Dirim and Caliskan 2012). This indicates both drum dried and vacuum oven dried powder are stable products. The differences in water activity of the drum dried and vacuum oven dried powder maybe due to the two separate drying techniques, which can be credited to the drying temperature utilized. A higher drying temperature used in drum drying resulted in lower water activity contrasted with vacuum drying (Caparino et al. 2012).

Hygroscopicity
Hygroscopicity is defined as the capacity of the food powder to uptake moisture from the environment with relative humidity superior to that of equilibrium (Ribeiro et al. 2016). The measure of hygroscopicity in powdered ingredients is an important parameter because the propensity for agglomeration is an impact attributed to the absorption of water on the surface of the particles. This makes the powder particles sticky and increases its tendency to form hydrogen bridges. Thus, this causes caking problems that inhibits the flowability of the powder (Goula and Adamopoulos 2008). Table 4.5 illustrates the hygroscopicity of drum dried and vacuum oven dried ambarella, Bintangor orange and Sarawak pineapple powder after a week of storage.
Table 4.5 Hygroscopicity of drum dried and vacuum oven dried of ambarella, Bintangor orange and Sarawak pineapple powder
Drum drying (%) Vacuum oven drying (%)
Ambarella 0.36±0.02a 0.25±0.02b
Bintangor orange 0.38±0.01a 0.34±0.01b
Sarawak pineapple 0.43±0.02a 0.22±0.02b
Data expressed in mean ± standard deviation based on triplicate readings (n=3). a-b Values in each row with different superscripts are significantly different at (p;0.05)
As shown in Table 4.5, the hygroscopicity of drum dried powder of ambarella, Bintangor orange and Sarawak pineapple were higher 0.11%, 0.04% and 0.21% compared to vacuum oven dried powder of ambarella, Bintangor orange and Sarawak pineapple respectively. According to Costa et al. (2014) found that the hygroscopicity of powder can be grouped into five stages in which powders less than 10% (non-hygroscopic), 10.1%-15% (slightly hygroscopic), 15.1%-20% (hygroscopic), 20.1%-25% (very hygroscopic) and more than 25% as extremely hygroscopic. Therefore, these results reflect those of Costa et al. (2014) studies in which the fruit powder were considered to be non-hygroscopic powder with percentage less than 10%. However, the reason of drum dried powder having a higher percentage of hygroscopicity is because of their drying conditions, which have high processing temperature and lower moisture content in the product making it capable of absorbing moisture from the surrounding (Tonon et al. 2008).
The variation in hygroscopicity percentages acquired from two different drying methods can be attributed to the different hygroscopic constituents such as citric acid and sugar, which have different glass transition temperatures found in different fruits (Ergun et al. 2010). During the drying operation, water which act as a plasticizer was removed in order for the liquid food to transform to a glassy state. If the drying temperature is higher than the glass transition temperature of the constituents, hence the food will not be converted to the glassy state. As a result, the end product will stay in a high-energy sticky state. According to Muzaffar et al. (2015) claims that sticky products tend to be more hygroscopic. Therefore, to ensure the end product remain in a low energy non-sticky state, the drying temperature should be lower than the glass transition temperature of constituents (Nurhadi et al. 2012).
In addition, difference in hygroscopicity percentage can also be caused by their size. This is because finer particles have bigger contact surface thus resulting in a higher number of active sites. The number of active site coming into contact with air will rise in the hygroscopicity percentage due to increase in water absorption (Ribeiro et al. 2016). However, the use of drying aids such as maltodextrin helps resolve hygroscopicity problems. An increase in the percentage of maltodextrin added to the powder decreases the hygroscopic values of the powder. This occurred because maltodextrin has low hygroscopicity, which can affect the existing affinity between water and other compounds in the product (Costa et al. 2014).
Degree of Caking
According to Mathlouthi and Roge (2003), caking is characterized as the lumping of food powder into solid and sticky material. This is caused by the unconstrained agglomeration phenomenon caused by liquid bridges. As the powder cakes it tends to reduce in functionality and fluidity (Zafar et al. 2017). Powder containing fruit sugars and fruit acids such as fructose, glucose, sucrose, citric acid and malic acid makes the powder difficult to be dried leading to the lower glass transition temperature. However, this problem can be overcome by the addition of drying aid such as maltodextrin which is added to raise the glass transition of the mixture. The powder still has a tendency to cake even after the addition of maltodextrin (Paterson and Brockel 2015). Table 4.6 shows the degree of caking of drum dried and vacuum oven dried ambarella, Bintangor orange and Sarawak pineapple powder.

Table 4.6 Degree of caking of drum dried and vacuum oven dried of ambarella, Bintangor orange and Sarawak pineapple powder
Drum drying (%) Vacuum oven drying (%)
Ambarella 10.47±0.97a 6.53±0.74b
Bintangor orange 12.31±0.80a 10.36±0.38b
Sarawak pineapple 9.44±1.27a 5.89±0.85b
Data expressed in mean ± standard deviation based on triplicate readings (n=3). a-b Values in each row with different superscripts are significantly different at (p;0.05)
Based on Table 4.6, the degree of caking of drum dried powder of ambarella, Bintangor orange and Sarawak pineapple were higher 3.94%, 1.95% and 3.55% than vacuum oven dried powder of ambarella, Bintangor orange and Sarawak pineapple respectively. To date, there are no further studies conducted on the degree of caking of drum dried and vacuum oven dried powders. However, the effect of caking occurs on surfaces of amorphous products caused by surface plasticization induced by water sorption. In addition, caking also occurs in water soluble powder that are exposed to high relative humidity environments (Domingo et al. 2017). Commonly, hygroscopicity of the powder leads to caking of the powder.
The study of Costa et al. (2014) found that powders with the degree of caking which are more than 50% are classified as extremely caking powder, 20% to 50% are classified as caking powder, 10% to 20% are classified as slightly caking powder and below 10% are classified as non-caking powder. These results are in agreement with Costa et al. (2014) findings in which vacuum oven dried ambarella, Sarawak pineapple and drum dried Sarawak pineapple are classified as non-caking powder whereas the drum dried ambarella, Bintangor orange and vacuum oven dried Bintangor orange are classified as slightly caking powder. Anti-caking agents are used in food powder to decrease the caking of powder and ensure stability of food products such as tricalcium phosphate and silicon dioxide (Lipasek et al. 2011).

Wettability
Wettability of a powder is described as the ability of powder particles being penetrated by a liquid without agitation because of the capillary forces, and becomes completely wet (Hogekamp and Schubert 2003). A substance known as scum will form if the powder is not able to wet sufficiently. This layer of scum will continuously stick together and form an obvious layer on the walls of the container (Fang et al. 2007). Wettability an important factor to determine the reconstitution properties of powder. In an analysis of wettability, Schuck et al. (2012), found that powder which are high in carbohydrates (MD DE 12, sorbitol, and maltitol), have wettability index that is less than 10 seconds while powder which are high in protein (caseinates and micellar proteins) and/or fats (whey 40% fat, whole egg, egg yolk, milk 26% fat), have wettability index that is more than 120 seconds and categorised as non-wettable powder. Table 4.7 describes the wettability properties of drum dried and vacuum oven dried ambarella, Bintangor orange and Sarawak pineapple powder.

Table 4.7 Wettability of drum dried and vacuum oven dried of ambarella, Bintangor orange and Sarawak pineapple powder
Drum drying (s) Vacuum oven drying (s)
Ambarella 64.08±1.68a 49.07±1.40b
Bintangor orange 56.62±1.44a 40.52±5.79b
Sarawak pineapple 49.56±4.52a 33.78±3.22b
Data expressed in mean ± standard deviation based on triplicate readings (n=3). a-b Values in each row with different superscripts are significantly different at (p;0.05)
As shown in Table 4.7, the wettability of drum dried powder of ambarella, Bintangor orange and Sarawak pineapple took a longer time of 15.01s, 16.1s and 15.78s compared to vacuum oven dried powder of ambarella, Bintangor orange and Sarawak pineapple respectively. One of the reason for drum dried powder took a longer time to completely wet compared to vacuum oven dried powder may be due to the decrease in powder residual moisture content. The lower moisture content in the drum dried powder resulted in a longer time taken to wet the powder completely compared to vacuum oven dried powder (Phisut 2012). The types of carrier used, such as maltodextrin also had a significant role in determining wettability. When the De value of maltodextrin is higher, the solubility of maltodextrin in water increases (Nurhadi et al. 2012).

In addition, according to Schuck et al. (2012), standards given in a diary sector indicating a powder with wettability index below 60 seconds is considered wettable and wettability index below 30 seconds is extremely wettable. Therefore, these results reflect those of Schuck et al. (2012) studies that drum dried and vacuum oven dried powder in this study excel good instant properties accept for drum dried ambarella powder. The drum dried ambarella powder have a wettability index more than 60 seconds (64.08 seconds) because the ambarella fruit had the highest fat content of 0.62 g than the other two fruits Tiburski et al. (2011). The chemical composition of higher fat content leads to higher presence of fat (free fat) on the surface of powder. This finding limits the wettability of the powder because of the hydrophobic nature of the free fats (Fang et al. 2007).
Flowability
Flowability of particulate solids of the powder was measured using the angle of repose (Kanha and Laokuldilok 2014). It is used as a predictor of possible flow difficulties that might arise in industrial applications and also used as a rough flowability indicator. The angle of repose is defined as the angle of the free surface of a heap of powder formed to the horizontal pane. In addition, if material is non-cohesive, the powder can flow smoothly as a low heap is formed. According to Begum et al. (2017), the dried powder’s ability to flow well and smoothly depends on various factors for instance the powder shape and size distribution, moisture content, electrostatic effects and particle size being the main factor. The smaller the particle size of the powder, the decrease in the powder flowability rate (Jinapong et al. 2008). Table 4.8 illustrates the flowability of drum dried and vacuum oven dried ambarella, Bintangor orange and Sarawak pineapple powder.

Table 4.8 Flowability of drum dried and vacuum oven dried of ambarella, Bintangor orange and Sarawak pineapple powder
Drum drying (°) Vacuum oven drying (°)
Ambarella 37.81±1.79b 43.01±1.07a
Bintangor orange 33.27±1.61b 42.09±0.66a
Sarawak pineapple 37.57±1.64b 43.91±1.42a
Data expressed in mean ± standard deviation based on triplicate readings (n=3). a-b Values in each row with different superscripts are significantly different at (p<0.05)
Based on Table 4.8, the vacuum oven dried powder of ambarella, Bintangor orange and Sarawak pineapple had the angle of repose of 43.01°, 42.09° and 43.91° were higher than drum dried powder of ambarella, Bintangor orange and Sarawak pineapple which had the angle repose of 37.81°, 33.27° and 37.57° respectively. Moreira et al. (2009) stated that free-flowing powder as powder having an angle repose below 45°. Therefore, all the fruit powders above have free-flowing properties which categorizes them as good flowability powder. To date, there is limited data on the flowability of drum dried and vacuum oven dried ambarella, Bintangor orange and Sarawak pineapple powder. The decrease in processing temperature decreases the powder flowability. This seems to be attributed to their higher moisture contents, since higher moisture content decreases the rate of powder flowability. This supports the results above, where the angle of repose in vacuum oven dried powder is higher than drum dried powder (Fitzpatrick 2005). The flowability of the powder can be improved by increasing the particle size of the powder, reducing the moisture of the powder and selecting the type of drying agent used (Moreira et al. 2009). For example, the drying agent of maltodextrin was replaced by cashew tree gum, which had an increase in the flowability of the powder.
Water Solubility Index (WSI)
Solubility is defined as reconstitution property which is used to determine the effect of process parameters in downstream processing because the physical and chemical functionality of food powder are only functional when it completely dissolves in a solution (Santhalakshmy et al. 2015). The water solubility index measures the ability of the powder to dissolve in water and express in terms of percentage by the difference between the volume of the reconstituted liquid and the volume of sediment (Schuck et al. 2012). The table 4.9 shows the water solubility index (WSI) of drum dried and vacuum oven dried ambarella, Bintangor orange and Sarawak pineapple powder.

Table 4.9 Water solubility index (WSI) of drum dried and vacuum oven dried of ambarella, Bintangor orange and Sarawak pineapple powder
Drum drying (%) Vacuum oven drying (%)
Ambarella 22.79±0.10a 19.51±0.11b
Bintangor orange 16.50±0.64b 23.25±0.16a
Sarawak pineapple 16.33±0.86b 23.64±0.24a
Data expressed in mean ± standard deviation based on triplicate readings (n=3). a-b Values in each row with different superscripts are significantly different at (p<0.05)
As shown in Table 4.9, the water solubility index (WSI) of drum dried powder of Bintangor orange and Sarawak pineapple were lower 6.75% and 7.31% than vacuum oven dried powder of Bintangor orange and Sarawak pineapple respectively. Laryea et al. (2017) obtained drum dried sweetpotato-based complementary food powder with a WSI of 13.75 to 18.20% which is in the range with WSI values obtained for the drum dried powders of Bintangor orange and Sarawak pineapple. The lower WSI of drum dried powder may due to the incomplete gelatinization of starch granules in the samples by drum drying process (Laryea et al. 2017). These results seem to be consistent with other research which found that WSI decreased along with the increase of drying temperature because high temperature used during processing will destroy the product surface as well as the pores that allowed re-enter of water into the sample (Dao 2015). However, the WSI of drum dried powder of ambarella was higher 3.28% than vacuum oven dried powder of ambarella. These results further supports the idea of Bansal et al. (2013) stating a higher temperature solution increases the water solubility index and produces low moisture powder with high surface area aid in simple and fast solubilisation of powder.

In addition, Sousa et al. (2008) obtained spray dried tomato powder with a WSI of 17.65-26.3% which is in the range with WSI values obtained for the drum dried and vacuum oven dried powders of ambarella, Bintangor orange and Sarawak pineapple but has lowest value compared to freeze dried soursop fruit powder with a WSI of 81.51-85.75% (Ceballos et al. 2012). The rate of solubility of powder is influenced by hydrophilic molecules, namely proteins on the surface of the powder. Proteins have soluble, polar buildups which can form hydrogen bond with water while the hydrophobic particle fold inwards and does not interact with water (Phisut 2012).
The difference in values of WSI between the drum dried and vacuum oven dried powder could be caused by the different storage period. Prolonged storage periods lead to the formation of a network of cross-linked proteins at the surface which act as penetration barrier to water, thus preventing reconstitution properties. Solubility of the powder is also affected by the pH (Fang et al. 2007). The WSI of powder can be improved by adding carrier agents such as maltodextrin and optimizing the conditions in the drum drying process. An increase amount of maltodextrin increases the rate of solubility in the powder because it can lessen the water holding capacity of powder (Vidovic et al. 2014). Optimizing the conditions in the drum drying process could result in a full starch gelatinization of granules therefore increasing the solubility of the complementary food (Laryea et al. 2017).

4.2.9Total Colour Change (?E)
Colour is an important parameter in food as it may indicates changes in food quality caused by processing, handling and storage (Roongruangsri and Bronlund 2016). In addition, colour also influences the degree of consumer acceptance and purchases made on food material. According to Zielinska and Markowski (2012) drying effect values of colour indices such as total colour change (?E). The reason colour change occurs in food is due to enzymatic browning reactions namely the browning of fresh and dehydrated fruits and vegetables, non-enzymatic browning reactions such as Maillard reaction and caramelization due to thermal processing of food at high temperatures (Patel et al. 2013). The table 4.10 describes the total colour change (?E) of drum dried and vacuum oven dried ambarella, Bintangor orange and Sarawak pineapple powder.
Table 4.10 Total colour change of drum dried and vacuum oven dried of ambarella, Bintangor orange and Sarawak pineapple powder
Drum drying (?E) Vacuum oven drying (?E)
Ambarella 40.17±2.14a 39.90±1.21a
Bintangor orange 37.66±1.35a 32.85±1.59b
Sarawak pineapple 21.92±0.46a 19.51±0.95b
Data expressed in mean ± standard deviation based on triplicate readings (n=3). a-b Values in each row with different superscripts are significantly different at (p<0.05)
Based on Table 4.10, both drum dried and vacuum oven dried powder ambarella powder had no significant difference at (p> 0.05) however, drum dried Bintangor orange and Sarawak pineapple powder had total colour change (?E) with values of 37.66 and 21.92 were higher compared to vacuum oven dried Bintangor orange and Sarawak pineapple powder which had to total colour change (?E) with values of 32.85 and 19.51. Zielinska and Markowski (2012) found that the indices of ?E* had an increasing trend with drying temperature and drying time hence resulted with a total difference in colour of fruit powders during drying. These results are in agreement with Albanese et al. (2013) findings which showed that the large difference in total colour change of the drum dried powder is closely related to the pigment degradation mainly carotenoids, formation of brown pigments by non-enzymatic reaction such as Maillard reaction and enzymatic reaction due to the high thermal processing temperature used. The smaller difference in colour of the vacuum oven dried powder is due to the lower processing temperature used leading to a lesser colour degradation (Ratti 2001).

4.3RECONSTITUTION ANALYSIS OF POWDER
4.3.1Reconstituted Colour
The reconstitution phenomenon of powder involves wetting, dispersing, sinking and dissolving the food powder (Koc et al. 2012). Solubility is the final step of powder dissolution and is considered as the most important phenomenon of the entire reconstitution of powder quality. The colour value of the reconstituted powder properties are directly influenced by the drying conditions such as drying temperature and drying time (Birchal et al. 2005). The table 4.11 illustrates the colour of reconstituted dried powders of ambarella, Bintangor orange and Sarawak using drum drying and vacuum oven drying.
As shown in Table 4.11, the clear tendency in significant changes of lightness during reconstitution were observed in parameter L*. Reconstituted vacuum oven dried powder of ambarella, Bintangor orange and Sarawak pineapple had value of of 36.10, 36.03 and 52.77 were lighter compared to drum dried powder of ambarella, Bintangor orange and Sarawak pineapple powder had value of 25.08, 28.33 and 33.83. As seen in the table, the drum dried Bintangor orange powder had a higher positive a* value of 4.40 compared to the vacuum oven dried Bintangor orange powder with a value of 2.99. The ambarella powder for both drum dried and vacuum oven dried had negative values tend to be more greenish. However, the drum dried ambarella powder with a value of -2.80 was more greenish than the vacuum oven dried ambarella powder with value of -1.32. For Sarawak pineapple, both drum dried and vacuum oven dried powder of the a* values had no significant difference at (p> 0.05).

For ambarella, both drum dried and vacuum oven dried powder of the b* values had no significant difference at (p> 0.05) however, the vacuum oven dried Bintangor orange and Sarawak pineapple powder with values of 37.87 and 11.55 tend to appear more yellowish compared to the drum dried Bintangor orange and Sarawak pineapple powder with values of 28.90 and -0.43 may be due to the longer drying time (Zielinska and Markowski 2012). Generally, the lightness in the Bintangor orange and Sarawak pineapple powder indicates the colour is affected by the addition of drying aid such as maltodextrin while the processing temperature of drying used affect both the a* and b* colour parameters (Fegus et al. 2015). An increase in the drying temperature during processing, decreases the value of redness and yellowness in the powder (Zielinska and Markowski 2012).

Table 4.11 Colour of reconstituted of drum dried and vacuum oven dried of ambarella, Bintangor orange and Sarawak pineapple powder
Colour Ambarella Bintangor orange Sarawak pineapple
L* a* b* L* a* b* L* a* b*
Drum drying 25.08±2.01b -2.80±0.15b 19.47±0.94a 28.33±2.19b 4.40±0.14a 28.90±3.80b 33.83±2.43b -0.48±0.02a
-0.43±0.03b
Vacuum
oven drying 36.10±0.78a -1.32±0.01a
18.76±0.68a 36.03±3.12a 2.99±0.38b 37.87±1.43a 52.77±2.13a -0.56±0.07a 11.55±0.78a
Data expressed in mean ± standard deviation based on triplicate readings (n=3). a-b Values in each column with different superscripts are significantly different at (p<0.05). Abbreviation: L* represents lightness and darkness, a* represents greenness and redness, b* represents blueness and yellowness
4.3.2Total Colour Change (?E)
Table 4.12 shows the total colour change of reconstituted dried powders of ambarella, Bintangor orange and Sarawak using drum drying and vacuum oven drying. The total colour change of reconstituted powder properties are directly influenced by the drying conditions such as drying temperature and drying time (Koc et al. 2012).

Table 4.12 Total colour change of reconstituted of drum dried and vacuum oven dried of ambarella, Bintangor orange and Sarawak pineapple powder
Drum drying (?E) Vacuum oven drying (?E)
Ambarella 24.33±2.97a 12.53±1.41b
Bintangor orange 39.95±2.06a 28.62±1.33b
Sarawak pineapple 49.34±2.13a 28.09±2.25b
Data expressed in mean ± standard deviation based on triplicate readings (n=3). a-b Values in each row with different superscripts are significantly different at (p<0.05)
As shown in Table 4.12 the total colour change of reconstituted drum dried ambarella, Bintangor orange and Sarawak pineapple powder were higher with values of 24.33 (?E), 39.95 (?E) and 49.34 (?E) compared to vacuum oven dried ambarella, Bintangor orange and Sarawak pineapple powder with values of 12.53 (?E), 28.62 (?E) and 28.09 (?E) . Thus, drum drying is a less preferable drying method since it is not able to maintain the original colour of powder leading to a higher change than vacuum oven drying. The large difference in colour of the drum dried powder could be caused by the high thermal processing temperature used may have resulted to colour degradation of pigment compound such as carotenoids (Grune et al. 2010).
4.3.3Beta Carotene Content Analysis
There are various types of carotenoids available in food such as lutein, lycopene and beta carotene. Carotenoids are the pigments that give food like orange and pineapple its vibrant yellow and orange colour (Rajauria and Tiwari 2017). However, the most common carotenoids in food are the alpha carotene and beta carotene (Higdon 2004). Beta carotene is an organic compound that has a vibrant red-orange pigment which is abundantly found in plants and fruits. Beta carotene pigments in fruits and vegetables are very sensitive to oxidation when exposed to light, heat and oxygen. For example, according to (Ghaboos et al. 2016) the colour loss in food products are due to oxidation of beta carotene which is caused by enzymes like lipoxygenase. In addition, beta carotene acts as a precursor for vitamin A and also acts as an antioxidant compound in preventing cancer and muscular degenaration (Johnson 2012). Table 4.13 describes the beta carotene content of drum dried and vacuum oven dried ambarella, Bintangor orange and Sarawak pineapple powder.
Table 4.13 Beta carotene content of drum dried and vacuum oven dried of ambarella, Bintangor orange and Sarawak pineapple powder
Puree
(µg/g) Drum Drying
Total Carotenoid Content
(µg/g) Vacuum Oven Drying
Total Carotenoid Content
(µg/g)
Ambarella 90.19±1.72ab 12.51±0.82b 27.65±3.58a
Bintangor orange 122.83±11.58ab 36.90±4.78b 67.41±8.36a
Sarawak pineapple 80.70±5.77ab 8.46±0.35b 11.37±1.60a
Data expressed in mean ± standard deviation based on triplicate readings (n=3). a-b Values in each row with different superscripts are significantly different at (p<0.05)
Based on Table 4.13, the beta carotene content of ambarella, Bintangor orange and Sarawak pineapple puree were originally high with values of 90.19 µg/g, 122.83 µg/g and 80.70 µg/g respectively. After drying the purees into powder, the total beta carotene content in the fruit powders decreased drastically. The beta carotene content of vacuum oven dried powder of ambarella, Bintangor orange and Sarawak pineapple were higher with values of 27.65 µg/g, 67.41 µg/g and 11.37 µg/g compared to drum dried powder of ambarella, Bintangor orange and Sarawak pineapple with values of 12.51 µg/g, 36.90 µg/g and 8.46 µg/g. The reason for this may be due to the lower processing temperature used in vacuum oven drying resulting in higher quality product (Sunjka et al. 2004). According to Kim (2012), oxidation of the beta carotene is also reduced since drying is done under an air-deficient environment.
The lower beta carotene content in drum dried powder may be due to their higher processing temperature and stickiness of the fruit, which sticks to the surface of the drum longer and this will lead to oxidation (Ghaboos et al. 2016). Since beta carotene is known to be sensitive to heat and light, increase in temperature causes beta carotene to degrade (Dao 2015). In addition, dehydration processes will lead to oxidation because an increased surface to mass ratio and of the exposure to oxygen (Ruttarattanamongkol et al. 2015).
4.3.4Vitamin C Content Analysis
Vitamin C is one of the most important water-soluble vitamin which is naturally present in fruits and vegetables. The human body is unable to synthesis vitamin C because of the lack of enzyme L-gulonolactone oxidase, thus vitamin C needs to be obtained through fruits and vegetables (Figueroa-Mendez and Rivas-Arancibia 2015). Vitamin C helps to protect the body from diseases such as scurvy and also preventing free radicals from attacking a healthy cell (Joy 2010). The degradation of vitamin C are affected by a few factors such as type of drying methods, temperature, oxygen, pH and the presence of enzymes whereas the storage condition affects the stability of vitamin C in foods (Fatin and Azrina 2017). Table 4.14 illustrates on the vitamin C content of drum dried and vacuum oven dried ambarella, Bintangor orange and Sarawak pineapple powder.
Table 4.14 Vitamin C content of drum dried and vacuum oven dried of ambarella, Bintangor orange and Sarawak pineapple powder
Puree
(mg/g) Drum Drying
Total Vitamin C Content
(mg/g) Vacuum Oven Drying
Total Vitamin C Content
(mg/g)
Ambarella 32.47±0.64ab 13.70±0.44b 19.72±0.78a
Bintangor orange 38.14±1.79ab 14.09±0.37b 16.34±1.05a
Sarawak pineapple 22.62±1.07ab 12.96±0.64b 15.13±0.36a
Data expressed in mean ± standard deviation based on triplicate readings (n=3). a-b Values in each row with different superscripts are significantly different at (p<0.05)
As shown in Table 4.14, the vitamin C content of ambarella, Bintangor orange and Sarawak pineapple puree were originally high with values of 32.47 mg/g, 38.14 mg/g 22.62 mg/g respectively. After drying the purees into powder, the total content of vitamin C in the fruit powders decreased. The vitamin C content of vacuum oven dried powder of ambarella, Bintangor orange and Sarawak pineapple were higher with values of 19.72 mg/g, 16.34 mg/g and 15.13 mg/g compared to drum dried powder of ambarella, Bintangor orange and Sarawak pineapple with values of 13.70 mg/g, 14.09 mg/g and 12.96 mg/g. Comparison with other studies also confirms vacuum oven dried powder was higher in vitamin C content because of the lower processing temperature used in vacuum oven drying (Sunjka et al. 2004). In addition, these results also reflect those of Kim (2012) who found oxidation of vitamin C is reduced since drying is done under an air-deficient environment.
The drum dried powder had lower vitamin C content. This result may be explained by the use of high temperature in the drum drying process which is only suitable for heat tolerant purees or heat resistant materials such as tomato purees and animal feed (Heldman 2003). This further explains the lower content of vitamin C in the drum dried powder due to vitamin C being a heat sensitive vitamin and easily evaporates at high temperature. In addition, the increase in rate of oxidation due to the exposure of the surface area to the environment is another factor leading to the lower content of vitamin C in the drum dried powder (Dao 2015). A possible explanation of vitamin C lost in ambarella, Bintangor orange and Sarawak pineapple powder was also because of the large surface area of the puree was exposed to air during the drying process, hence increasing the lost of vitamin C. However, inert gases as a drying medium can be used to minimise this problem (Marfil et al. 2008).

Chapter V
CONCLUSION
5.1CONCLUSION
In this investigation, this study aimed to compare the effects of drum drying and vacuum oven drying on the process yield, physicochemical properties, reconstituted properties, beta carotene and vitamin C content in the powder were successfully determined for ambarella, Bintangor orange and Sarawak pineapple powder. Vacuum oven drying of ambarella, Bintangor orange and Sarawak pineapple powder had higher process yield (36.51%, 43.27% and 38.80%) than drum dried ambarella, Bintangor orange and Sarawak pineapple powder (20.79%, 31.13% and 21.21%).
For the physicochemical analysis, the moisture content and water activity of drum dried powder of ambarella, Bintangor orange and Sarawak pineapple was lower than vacuum oven dried powder. The decrease in moisture content and water activity of drum dried powder led to a better flowability rate of powder with a lower angle repose of 37.81°, 33.27° and 37.57° respectively. However, the vacuum oven dried powder was lower in hygroscopicity, degree of caking and reduce in wettability time compared to drum dried powder of ambarella, Bintangor orange and Sarawak pineapple. Water solubility index of ambarella, Bintangor orange and Sarawak pineapple powder was higher in vacuum oven drying than drum drying. Nevertheless, drum dried ambarella powder had a better solubility with value of 22.79% than vacuum oven dried ambarella powder with value of 19.51%. As for colour analysis result showed that, the vacuum oven dried powder retained the colours of the powder to the colour of the original puree. For reconstituted analysis, vacuum oven dried powder had lesser total colour change, retained a higher quantity of beta carotene and vitamin C content rather than drum dried powder of ambarella, Bintangor orange and Sarawak pineapple.
The results of this study indicate that, vacuum oven drying is a desired drying method because the powder have a higher yield which is a critical factor in mass productions. Besides that, vacuum oven drying had an acceptable range of moisture content and water activity. In addition, vacuum oven dried powder were non-hygroscopic, non-caking powder, better wettable properties and more soluble except for drum dried ambarella powder. All these factor aid in extending the storage period of the powder. Although, the flowability of drum dried powder is better than vacuum oven dried powder but the vacuum oven dried powder is still consider to have free-flowing powder properties. In terms of beta-carotene and vitamin C nutrient content, vacuum oven drying retain a higher rate of both the nutrients.
5.2LIMITATIONS OF STUDY AND FUTURE RECOMMENDATIONS
There were few limitations found throughout the study and some improvements could be done in the future. Firstly, only two types of drying methods were compared in this study due to the decrease on the availability of the drying equipment. Secondly, microbial test was not carried out because this study was not done under a sterile environment. In order, for a better characterization of physicochemical and reconstituted properties of the powder, microbial test should be done to ensure the powder is safe for consumption and free from all foodborne pathogens. Moreover, ensuring the packaging material of the powder is nitrogen-flushed because it may retain the quality and enhance the stability of the powder.
Further studies need to be carried out in order to validate a more accurate, precise and consistent result on beta-carotene content and vitamin C content present in the powder. It is highly recommended to use HPLC method. In addition, sensory evaluation test should be conducted before the food product is introduced into the market. Sensory evaluation is done to determine the consumer’s acceptability on the product, hence improving the product’s appearance, texture, taste and smell according to the consumer’s preferences so the food product is marketable. Nevertheless, this fruit powder serves a variety of application in the future market such as being use as ingredients in the final food products. Besides that, being use in various seasoning products such as pineapple flavoured cheese powder and orange-lime flavoured powder for snack seasonings. Lastly, the fruit powder may also be use in nutraceutical products, ayurvedic body scrubs and baby foods. Hence, the most suitable drying method can be selected which shows a positive effect on the physicochemical, reconstituted properties and in retaining the beta carotene and vitamin C content in the powder.

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APPENDIX A
List of Chemicals and Reagents
Chemical/ Reagent Purity Supplier, Country
Physicochemical analysis Sodium chloride – Friedemann Schmidt, Germany
Beta-carotene content Acetone ? 99.8 % Merck Kgaa, Germany
Petroleum ether 35-60°C Friendemann Schmidt, Germany
Sodium sulphate anhydrous – QRec, New Zealand
Beta-carotene powder ? 97.0 % Millipore-Sigma, Germany
Vitamin C content Iodine – QRec, New Zealand
Potassium iodide – QRec, New Zealand
Starch soluble – Friedemann Schmidt, Germany
Maltodextrin DE 10-12 Bronson and Jacobs, Australia
APPENDIX B
List of Apparatus and Equipment
Apparatus/ Equipment Model Manufacturer, Country
Analytical balance XT220A Precisa, Switzerland
Centrifuge machine 5702 Eppendorf, Germany
Convection oven UFB 500 Memmert, Germany
Desiccator – –
Digital refractometer PAL-1 (0-32° Brix) Atago, Japan
Drum dryer – R.Simon (Dryers) Ltd. Nottingham, England
Food processor MK-5076 Panasonic, Japan
Grinder 8011S America
Halogen moisture analyzer –
Mettler Toledo, Switzerland
Hotplate stirrer HTS-1003 LMS Harmony, Japan
HunterLab colorimeter ColorFlex Ez Hunter Associates Laboratory, Inc, United States
Rotary evaporator B-490, R-200 Buchi, Switzerland
Spectrophotometer UviLine 9400 Secomam, France
Vacuum oven dryer VD 23 Binder, Germany
Water activity meter Aqua Lab Novasina, Switzerland
Water bath – Memmert, Germany
APPENDIX C
Standard Curve of Carotenoid Content

APPENDIX D
List of Different Percentage Yield for Different Percentage of Maltodextrin Incorporated in Fruit Puree
Percentage of maltodextrin incorporated in fruit puree (%) Percentage yield of fruit powder for drum drying (%) Percentage yield of fruit powder for vacuum drying (%)
10 (ambarella)
10 (Bintangor orange)
10 (Sarawak pineapple) 10.05
9.78
9.17 15.33
13.10
12.53
15 (ambarella)
15 (Bintangor orange)
15 (Sarawak pineapple) 12.71
13.37
13.08 22.53
20.35
21.38
20 (ambarella)
20 (Bintangor orange)
20 (Sarawak pineapple) 15.06
20.23
16.15 29.03
31.37
25.12
50 (ambarella)
50 (Bintangor orange)
50 (Sarawak pineapple) 20.79
31.13
21.21
36.51
43.27
38.80

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