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UNIVERSITI PUTRA MALAYSIA
DEVELOPMENT OF DURIAN LEATHER AND DETERMINATION OF ITS FLAVOUR RETENTION
DURING PROCESSING AND STORAGE
IRWANDI
FSMB 1996 5
DEVELOPMENT OF DURIAN LEATHER AND
DETERMINATION OF ITS FLAVOUR RETENTION DURING PROCESSING AND STORAGE
BY
mWANDI
Thesis Submitted in FulfIlment of the Requirements for the Degree of Master of Science in
the Faculty of Food Science and Biotechnology, Universiti Pertanian Malaysia
December, 1996
ACKNOWLEDGEMENTS
Alhamdulillah, first of all I would like to express my utmost thanks and
gratitude to Almighty Allah SWT who has given me the will and strength to complete
this project and salawat and salam to His righteous messenger, Prophet Muhammad
SAW.
I would also like to express my most sincere appreciation and deepest
gratitude to Assoc. Prof Dr. Yaakob Bin Che Man, the Chairman of my Supervisory
Committee for his kind understanding, assistance, advice and guidance during the
course of this study and in the preparation of this thesis. I am also grateful to other
members of the Supervisory Committee: Assoc. Prof Dr. Jinap Selamat. Assoc. Prof
Dr. Salmah Yusof and Prof Dr. Hiroshi Sugisawa for their supervision, support and
comments.
I would like to acknowledge the financial support provided by the IRPA fund
for this research, which was awarded to Assoc. Prof Dr. Yaakob Bin Che Man. I
would also like to acknowledge Assoc. Prof Dr. Faujan Ahmad of the Chemistry
Department, UPM and Assoc. Prof Dr Mohd. Ambar Yarmo and Mr. Mohd Noor
Ibrahim of UKM for their assistance in GCIMS analysis. My deep appreciation is
also extended to the following laboratory assistants of the Faculty of Food Science
and Biotechnology: Mr. Azhar Mohd. Noor, Mr. Soib Yuso.t: Mr. Amran Suratman,
Mr. Halim Abdul Rahman and Mr. Chan Tin Wan for their technical help; and also to
my good mends: Fauzi Mohd. Ali, Muhd. Edwin Lubis, Tri Haryati, Rohaizah
Ahmad, Amin Ismail and Felix Moh for their generous assistance.
Last but not the least, I wish to express my deepest gratitude to my beloved
parents, brothers and sisters for their endless encouragement, patience and sacrifices
which had helped me in undertakings and completing this research study. I also owe
my special thanks to my special friend, Desi for her moral encouragement and
support.
� dedicated to
my beloved parents
TABLE OF CONTENTS
ACKN"OWLEDGEMENTS.................................................................. 1
LIST OF TABLES .......................................................... ............. ...... IX
LIST OF FIGURES ............................................................................ xu
LIST OF PLATES .... . .. ............ ......... . ..... . . . ...... ........ ................. . . . ....... xv
ABSTRACT ....... ......... .................. ... ...... ......... ....... ...... ....... ..... .......... XVI
ABS1RAK . . . ............ .... . . . .. . . . . .. . . . . . . . . . . . ........ . . .... . . . . . . .. .. . . . . . ..... . . ... . . . . . . . . . XIX
CHAPTER
1
2
GENERAL INTRODUCTION ................................ .
REVIEW OF LITERATURE . ................................ .
Botany, General Characteristics and Production ofDurian .................................................................... .
0· , dD" b ' ngms an lstn utIons ................................ ..
Agronomy ...................................................... .
Fruit Characteristics ....................................... .
Production .................................................... .
Chemical Composition ofDurlan ............................. .
Food Uses ofDurian ............................................. .
Extending the Shelf-life of Fresh Durian ........
Processed Durians ......................................... .
Fl . C · fDuri avounng onstltuents 0 an .......................... ..
Fruit Leather ............................................................ .
1
5
5
7
8
9
9
12
17
17
20
28
30
3
4
PERPUSTAKAAN tlNlVERSITI PUTRA MALAYSIA
PRELIMINARY STUDY ON DEVELOPMENT
OF DURIAN LEATHER FORMULATION ........ . 34
Introduction .............................................................. 34
Materials and Methods ............................................. 35
Materials .. .............................. ........ ............... 35
Sample Preparation........................................ 36
Physico-chemical Analyses............................. 36
Microbial Analyses........................................ 36
Sensory Analysis........................................... 3 8
Results and Discussion ............................................ 39
Composition ofDurian Leather and Durian Pulp.................................................. 39
Physico-chemical Characteristics of Durian Leather. ...... ...... . . . .. . . . . . . . . . . . ... . . . . . . . . . . . . . 39
Microbial Assay........................................... 43
Sensory Evaluation...................................... 43
Conclusion.............................................................. 46
EFFECT OF GLUCOSE SYRUP SOLID, SUCROSE, HYDROGENATED PALM OIL AND SOY -LECITHIN ON SENSORY PROPERTIES OF DURIAN LEATHER . . .. ....... . 47
Introduction...... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Materials and Methods ....................... ................... 50
Materials ............ .................. ... ............. ....... 50
Experimental Design ....................... ............ 50
Formulation Stage 1.................................... 50
Formulation Stage 2.................................... 52
5
6
Sensory Evaluation...................................... 52
COmpoSItion............. .......... . . . . . . . . . . . . . . . . . . . . . . . . . 52
Results and Discussion ........................................... 53
Formulation Stage 1.................................... 53
Formulation Stage 2. . .. . . . . . . .. . . . . . . . . . . . . . . . . . . . .. . . . 56
COmpoSItIon .................................... . .......... 61
Conclusion.............................................................. 68
EFFECT OF DIFFERENT DRYERS AND DRYING CONDITIONS ON ACCEPTABILITY AND PHYSICO-CHEMICAL CHARACTERISTICS OF DURIAN LEATHER .......................................................... . 69
Introduction ........................................................... 69
Materials and Methods ............................................ 71
Materials.......................................... ............ 71
Experimental Design..................................... 71
Sample Preparation .................................... . 72
Sensory Evaluation.......... ............ .... ... . . . . .... . . 73
Physico-chemical Analyses............................ 73
Results and Discussion ........................... ................ 74
Optimization Based on Sensory Evaluation........................................ ............. 74
Effect of Drying on Physico-chemical Properties .......................... .......................... 84
Conclusion.............. .............................. ....... ............ 94
STABILITY OF DURIAN LEATHER IN DIFFERENT PACKAGING MATERIALS ... . . .... 95
Introduction............................................................. 95
7
Materials and Methods ............................. .. ............. 96
Materials..... . .................... ... . . ............ . . . ........ 96
Experimental DesIgn..... .................... .. ......... 97
Sample Preparation..... . . ....... .. .... . . ..... .... . . ..... 97
Physico-chemical Analyses .............. ............ 98
Microbiological Tests.................................. 99
Sensory Evaluation. . . . . .... . ..... . .. .... . . ..... . . ....... 99
Results and Discussion .... . . ...... .. ... . ... . . ...... . . ..... . ...... 100
Physico-chemical Changes ofDurian Leather during Storage......... . ............. . ......... 100
Microbial Analyses .. . .......... . . ...... . . ....... ....... 120
Sensory Characteristics during Storage.... ................. . .... ............ . . ................. 125
Conclusion... . . .. ......... .... . ................. .... . ............. ....... 132
EFFECT OF PROCESSING CONDITIONS AND STORAGE ON RETENTION OF VOLATaE COMPONENTS OF DURIAN LEATHER ............................................................ " 133
Introduction.. ... . . .. ....................... .... . . ........................ 133
Materials and Methods ............ . ....... . ........... . ............ 133
Materials . .......... . . .. . .... . .... . ... . . ... . ..... ............. 135
Preparation ofDurian Leather..... . ................. 135
Experimental Design . ............. . ........ ....... . . .... 136
Extraction and Concentration of Volatile Components .. .. . . ........ . ....... . . .. . ..... .... 136
Identification of Volatiles .... .. . . ....... . . . . ......... . . 139
8
Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ......... . 139
Volatile Flavouring Constituents of Fresh Durian Aril ...... . . .... ... . . . .. . .. .. . . . . . . . . .. .. 139
Flavouring Components of Durian Leather .. . .. . . .. ...... . . . . . .. . . . . . ... . . . . .... . . . . . .. . 146
Retention of Volatile Components of Durian Leather during Storage . . . ... . . . . .. . . . . . 151
Conclusion. . . . . . . . . . . . . ................................. ................... 161
SUMMARY, CONCLUSION AND RECOMMENDATION ........................................ . 162
Summary . . ..... . . . . . . . . ................................... .............. 162
Conclusion and Recommendation. . . . . . . . . . . . . . . . . . .. . . . . . . . . . 165
BIDLIOGRAPHY .. .. . . . . .. . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . .. .. . . . . . . . . ... . .. . . .. . 167
APPENDICES .... . . ...... ....... .......... .............. .......... ................ ........ 1 76
PUBLICATION ..... . . . . . . ... . . . . . ..... . . . .......... . . . . ...... . . . . . .. . ... . . . . . .... ..... . . . 187
BIOGRAPHICAL SKETCH. . . . . . . . . . . .... . .... . . . . ........... ............... ....... 199
Vlll
LIST OF TABLES
Table Page
1 Recent Production of Durian in the Main Producing Countries (tonnes) .............................................................. . 10
2 Durian Hectarage in Peninsular Malaysia (1988- 1992) ......... 10
3 Value ofDurian Export from Malaysia .............................. .. 1 1
4 Area Planted, Yield and Production ofDurian in Indonesia, 1988-1992 ..................................................... . 12
5 Nutrient Composition of Fresh Durian (in 100g Edible Portion) ................ . . .... . . . .......... .......................................... . 14
6 Proximate and Mineral Composition of Some Wild Durians Found in Sabah and D. zibethinus ..... ..................... . 15
7 Lipid Content and Fatty Acid Composition of Four Durian Clones .................................................................... . 16
8 Fatty Acid Composition ofDurian Aril in Thailand (in % Peak Area) ............................................................... . 16
9 Chemical Composition of Lempuk. ...................................... . 22
10 Nutrient Composition of Tempoyak (in 100g edible portion) ............................................................................ . 24
1 1 Volatile Flavouring Compounds ofDurian ........................ .. 29
12 Proximate Composition of Fruit Leathers . ............... ..... ..... . 33
1 3 Composition of and Durian Leather Formulation and Fresh Durian Aril ....................................................... .. 40
14 Physico-chemical Properties of Various Formulation of Fresh Durian Leather .................................................... . 41
15 Effect Storage Time on Physico-chemical Characteristics of Durian Leather ............................................................. . 42
16 Effect of Storage Time on Sensory Attn'butes Characteristics ofDurian Leather Formulations ................ . 45
1 7 Effect of Glucose Syrup Solid and Sucrose on Taste and Aroma Scores ........................................................... 54
18 Regression Coefficient, R2 and P of F for Taste and Aroma Scores of Durian Leather .............................. 55
19 Effect of HPO and SL on Sensory Scores of Durian Leather .......... ......... ..... ..................... ............... . .. ............ 59
20 Regression Coefficient, R2 and P of F Values for Sensory Attributes of Durian Leather ............................. 60
21 Composition of Durian of Clone D24 and Durian Leather ................................................................. 6 7
2 2 Formulation of Main Ingredients ofDurian Leather and Commercialized Apple Leather . . . ... . . . . . . . . .... .. .. . .... . . . . 68
23 Combinations of Temperature and Time of Drying Obtained in Preparation ofDurian Leather ........................ 72
24 Sensory Evaluation for Oven-dried Durian Leather ... ......... 75
25 Sensory Evaluation for Cabinet-dried Durian Leather ......... 76
26 Regression Coefficients, R2 and P of F Values for Sensory Attributes of Oven-dried Durian Leather .............. 7 7
27 Regression Coefficients, R2 and P of F Values for Sensory Attributes of Cabinet-dried Durian Leather ........... 78
28 Regression Coefficients, R2 and P of F Values for Physico-chemical Properties of Oven-dried
Durian Leather .................................................................. 85
29 Regression Coefficients, R2 and P of F Values for Physico-chemical Properties of Cabinet-dried
Durian Leather ................................................................ 86
3 0 Mean Values and Standard Deviation for Moisture, Water Activity, Non-enzymatic Browning and pH of
Durian Leather during Storage ............................... .......... 101
3 1 Mean Values and Standard Deviation for Texture, L, a and b Colour ofDurian Leather during Storage ......... 102
32 Mean Values and Standard Deviation for Sugar, Fat and Caloric Content of Fresh and 12 Weeks Stored Durian Leather ............................................................... 103
33
34
35
36
37
38
Mean Values and Standard Deviation for Total Meshopilic Bacteria (TMB) and Total Mould and Yeast (TMY) Counts ofDurian Leather during Storage .............. ....... . . . . . ..................... . ............... . . . .. . .. . . . . .
Mean Values and Standard Deviation for Sensory Characteristics ofDurian Leather during Storage ............. .
Volatile Flavouring Components ofDurian .................... . .
Ten Major Compounds in Durian of Clone D24 ............. ..
Volatile Flavouring Components of Cabinet-dried Durian Leather ............................................................... .
Volatile Flavouring Components of Oven-dried Durian Leather ................................................................ .
121
126
140
144
147
149
LIST OF FIGURES
Figure Page
2
3
4
5
6
7
8
9
10
11
12
13
14
Preparation ofOuriall Leather........................................ 37
Total Mould Count ofDurian Leather .......................... .
Flow-chart of Preparation ofDurian Leather for the Ingredient F onnulation ....................................... .
Contour Map of the Effect of GSS and Sucrose on Taste ofDurian Leather ................................................. .
Contour Map of the Effect of GSS and Sucrose on Aroma ofDurian Leather ............................................. ..
Contour Map of the Effect ofHPO and SL on Taste of Durian Leather .......................................................... ..
Contour Map of the Effect ofHPO and SL on Texture ofDurian Leather ........................................................... .
Contour Map of the Effect ofHPO and SL on Aroma of Durian Leather ........................................................... .
Contour Map of the Effect of HPO and SL on Appearance ofDurian Leather ....................................... .
Contour Map of the Effect ofHPO and SL on Overall Acceptability of Durian Leather ........................... .
Contour Maps of the Effect of Temperature and Drying Time on the Sensory Attributes of Oven-dried Leather .................................................... ..
Contour Maps of the Effect of Temperature and Drying Time on Sensory Attributes of Cabinet-dried Leather . . .................. ............ ............ . . ................... .
Contour Maps of the Effect of Temperature and Drying Time on Physico-chemical of Oven-dried Ourian Leather ................................................................. .
Contour Maps of the Effect of Temperature and Drying Time on Physico-chemical Properties of Cabinet-dried Durian Leather ............................................ .
44
51
57
58
62
63
64
65
66
80
82
88
90
15 Changes in Moisture Content of Durian Leather during Storage: A (Oven), B (Cabinet) ............................ . 104
16 Changes in Aw ofDurian Leather during Storage: A (Oven), B (Cabinet) .............................................. .... .. 105
17 Changes in Non-enzymatic Browning ofDurian Leather during Storage: A (Oven), B (Cabinet) .............. . 109
18 Changes in Hunter L Value ofDurian Leather during Storage: A (Oven), B (Cabinet) .......................... .. 110
19 Changes in Hunter a Value of Durian Leather during Storage: A (Oven), B (Cabinet) .......................... .. 111
20 Changes in Hunter b Value ofDurian Leather during Storage: A (Oven), B (Cabinet) ......................... .. 112
21 Changes in Texture ofDurian Leather during Storage: A (Oven), B (Cabinet) .................................................... . 116
22 Changes in pH ofDurian Leather during Storage: A (Oven), B (Cabinet) .... ........................... . . . . .................. . 1 18
23 Changes in TMB of Durian Leather during Storage: A (Oven), B (Cabinet) ..................................................... . 123
24 Changes in TMY ofDurian Leather during Storage: A (Oven), B (Cabinet) ..................................................... . 124
25 Changes in Taste of Durian Leather during Storage: A (Oven), B (Cabinet) ..................................................... . 127
26 Changes in Texture ofDurian Leather during Storage: A (Oven), B (Cabinet) .................................................... .. 128
27 Changes in Aroma of Durian Leather during Storage: A (Oven), B (Cabinet) ..................................................... . 129
28 Changes in Appearance ofDurian Leather during Storage: A (Oven), B (Cabinet} ........................................ . 130
29 Changes in Overall Acceptability of Durian Leather during Storage: A (Oven), B (Cabinet) ............................ .. 13 1
30 Simultaneous Steam Distillation Extraction (SDE) .......... .. 137
31 Kudema-Danish Evaporator ............................................. . 138
X111
32 Gas Chromatograms of Volatile Components of Fresh Durian Aril . . . . . . ................................... . . . . . . . . . . . . . . 143
33 Gas Chromatograms of Volatile Components of Cabinet-dried Durian Leather . ... . . ... . .. .. ... ...... . ... . . . ....... 153
34 Gas Chromatograms of Volatile Components of Cabinet-dried Durian Leather at Week 4 ..................... 154
35 Gas Chromatograms of Volatile Components of Cabinet-dried Durian Leather at Week 8 ..................... 155
36 Gas Chromatograms of Volatile Components of Cabinet-dried Durian Leather at Week 12 ................... 156
37 Gas Chromatograms of Volatile Components of Oven-dried Durian Leather. . ... . . . . . . . .. . . ... . .... . . .. ... . . ...... . . . 157
38 Gas Chromatograms of Volatile Components of Oven-dried Durian Leather at Week 4 ......................... 158
39 Gas Chromatograms of Volatile Components of Oven-dried Durian Leather at Week 8 ......................... 159
40 Gas Chromatograms of Volatile Components of Oven-dried Durian Leather at Week 12 ....................... 160
LIST OF PLATES
fuh hp
2
3
4
5
6
7
8
9
lO
11
A Durian Tree Grown in Malaysia . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . . ... . . 6
Some Types of Fruit Leather FOWld in the Market.. ........... .
Oven-dried Durian Leather ............................................... .
Cabinet-dried Durian Leather ............................................ .
Durian Leather .................................................................. .
Forced-Air Cabinet Dryer .................................................. .
Oven Dryer . . ...... . . . . . . . . . . . . . . . .. . . . . . . ........ ... ....... ..... . . . . . . . . . ........ .
Adiabatic Oxigen Bomb Calorimeter ................................ .
Simultaneous Steam Distillation Extraction (SDE) ........... . .
Kudema-danish Concentrator ........................................... .
Gas Chromatography-Mass Spectrometry (Ge/MS) ......... .
3 1
92
92
183
184
184
185
185
186
186
Abstract of the Thesis Presented to the Senate of Universiti Pertaruan Malaysia in Fulfilment of the Requirements for the Degree of Master of Science.
DEVELOPMENT OF DURIAN LEATHER AND DETERMINATION OF ITS FLAVOUR RETENTION DURING PROCESSING AND STORAGE
BY
IRWANDI
December, 1996
Chairman: Associate Professor Yaakob Bin Che Man, Ph.D.
Faculty : Food Science and Biotechnology
Durian (DuriO zibethinus Murr) is a popular seasonal fruit grown in many
parts of South-East Asia. Malaysia, Thailand and Indonesia are major producers of
this fruit in the world. Today, durians are not only planted in home garden but also
grown commercially in large-scale plantation to meet the local and export demands.
Normally, durians are eaten shortly after harvest in fresh form as it quickly turns sour
and rancid due to some chemical changes that follow. To a lesser extend, durian is
also processed into products like lempuk (durian cake) and tempoyak (fermented
durian), two traditional products widely consumed in Malaysia and Indonesia.
However, these product are not commercially produced in large quantities.
Meanwhile, fruit leather, a product prepared by dehydration of fruit puree, is an
established product particularly in the North American and European markets;
however it is relatively unknown product in Malaysia. Therefore, the development of
XVI
a new fruit leather from durian could be an alternative to increase the commercial
value of durian.
Four aspects in the development of durian leather were conducted in this
study. These were preliminary study on the development of durian leather,
optimization of formulation and drying conditions of durian leather, product stability
during storage and determination of the retention of its flavouring components during
processing and storage. fu the preliminary study, the results showed that processing
of durian leather was feasible to diversifY the use of durian. Proximate composition of
the leather was comparable to other fruit leathers in the market. The product was
relatively stable and showed low mould counts and organoleptically acceptable in all
attnlmtes studied during three months storage.
Optimizations of ingredient formulation and drying conditions were carried
out using Response Surface Methodology (RSM) technique. The results based on
sensory evaluation showed that the most acceptable formulation was an ingredient
combination of 10% glucose syrup solid, 5% sucrose, 2.67% hydrogenated palm oil
and 0.45% soy-lecithin added into durian aril for the preparation of durian leather.
Optimum drying conditions were 50°C for 12.6 h for oven-dried leather, and 52.5°C
for 10 h for cabinet-dried leather.
A storage study on the optimum formulation and processing conditions
indicated that durian leather was a stable product up to 12 weeks storage. All samples
packed in four different types of packaging materials i. e. laminated aluminium foil
XVll
(LAF), high-density polyethylene (HDPE), low-density polyethylene (LDPE) and
polypropylene (PP), were shown to be organoleptically acceptable by the panelists.
LAF, however, was proven to be the finest packaging material in maintaining the
stability of durian leather during storage.
Determination on flavour retention in durian leather revealed that the
processing condition was relatively good to retain the durian aroma. At least, 26 of
38 fresh durian volatile flavouring components were still detected in durian leather.
During storage, the relative proportions of acids in durian leather increased, esters,
alcohols and aldehydes decreased, while hydrocarbons and phenolic compounds
fluctuated. However, the two types of dryer used exhtoited different phenomenon for
sulphurous (S) and nitrogenous (N) compounds. For cabinet-dried leather, the
proportion of S and N compounds decreased, while for oven-dried leather, the
proportion fluctuated during 12 weeks storage.
Y\/111
Abstrak T esis yang Dikemukakan kepada Senat Universiti Pertanian Malaysia sebagai Memenuhi Syarat untuk Ijazah Master Sains
PERKEMBANGAN PRODUK KEPINGAN DURIAN DAN PENENTUAN PENGEKALAN CITARASANYA SEMASA PEMPROSESAN AND
PENYIMPANAN
Oleh
mWANDI
Pengerusi : Profesor Madya Dr. Yaakob Bin Che Man
Fakuhi : Sains Makanan dan Bioteknologi
Durian (Durio zibethinus Murr) merupakan buah bermusim yang popular dan
banyak tumbuh di kawasan Asia Tenggara. Malaysia, Thailand and Indonesia adalah
negara-negara pengeluar buah durian yang utama di dunia. Pada masa kini, durian
tidak hanya ditanam di persekitaran rumah, tetapi telah ditanam di ladang-Iadang
besar untuk memenuhi keperluan tempatan dan ekspot. Kebiasaannya durian dimakan
secara segar sebaik dipungut kerana ianya cepat berubah menjadi masam disebabkan
perlakuan tindak-balas kimia. Secara kecil-kecilan, durian juga diproses menjadi
lempuk atau tempoyak, dua jenis produk yang disukai rarnai di Malaysia dan
Indonesia. Tetapi, produk-produk ini tidak dikeluarkan secara komersial.
Sementara itu, kepingan buah-buahan, iaitu produk yang disediakan secara
mengeringkan puri buah, merupakan produk yang sudah mendapat tempat di
Amerika Utara dan Eropah, tetapi belum begitu dikenali di Malaysia. Oleh itu,
perkembangan sesuatu produk kepingan buah-buahan yang barn daripada durian boleh
meningkatkan nilai komersia1nya.
Empat aspek dalam perkembangan produk kepingan durian telah dijalankan
dalam kajian ini. In termasuk kajian awal perkembangan produk kepingan durian,
pengoptimuman formulasi dan keadaan pengeringan, stabiliti kepingan durian semasa
penyimpanan dan pengukuran pengekalan komponen citarasa produk kepingan durian
semasa pemprosesaan dan penyimpanan. Di dalam kajian awal, didapati bahawa
pemprosesan produk kepingan durian adalah memungkinkan untuk mempelbagaikan
pemanfaatan buah durian. Komposisi proksimat menunjukkan bahawa kepingan
durian setanding dengan kepingan buah yang lain di pasaran. Produk kepingan durian
adalah stabil, rendah hitungan kulat dan melalui ujian deria, diterima dari semua ciri
eiri deria yang diuji semasa tiga bulan dalam simpanan.
Pengoptimuman formulasi dan keadaan pengenngan dilakukan dengan
menggunakan teknik "Random Surface Methodology" (RSM). Berdasarkan pengujian
deria, formulasi yang paling diterima ialah penggunaan kombinasi 10% sirap
glukosa pepejal, 5% gula sukrosa, 2.67% minyak kelapa sawit terhidrogenasi dan
0.45% lesitin kacang soya, yang ditambahkan kepada puri durian ketika penyediaan.
Keadaan pengeringan optimum ialah pada 500e selama 12.6 jam bagi kepingan
durian yang dikeringkan menggunakan oven, dan bagi produk yang dikeringkan
dengan pengering kabinet pula pada 52.2°e selama 10 jam.
Kajian stabiliti keatas formulasi dan keadaan pengermgan optimum
menunjukkan bahawa kepingan durian merupakan produk yang stabil sehingga 12
minggu penyimpanan. Semua sampel yang dI"bungkus dengan empat jenis bahan
pembungkus yang berlainan iaitu kepingan aluminium berlaminat (LAF), polietilena
berketumpatan tinggi (HDPE), polietilena berketumpatan rendah (LDPE) dan
polipropilena (PP), menunjukkan secara organoleptik, masih diterima oleh ahli panel. . .
LAF, bagaimanapun, merupakan bahan pembungkus yang paling baik dalam
pengekalan kestabilan kepingan durian sewaktu penyimpanan.
Pengukuran terhadap pengekalan citarasa durian menunjukkan bahawa
keadaan pemprosesan adalah baik dalam mempertahankan aroma durian.
Sekurangnya-kurangnya, 26 daripada 38 komponen meruap dalam buah durian segar
masih dikesan di dalam kepingan durian. Sewaktu penyimpanan, secara relatif nisbah
asid dalam kepingan durian meningkat, ester, alkohol dan aldehid menurun, manakala
hidrokarbon dan komponen fenolik tidak konsisten. Walaubagaimanapun, bagi
komponen sulfur (S) dan nitrogen (N), kedua jenis pengering yang digunakan
menunjukkan fenomena yang berbeza. Bagi kepingan durian yang dikeringkan dengan
pengering kabinet, komponen S dan N menurun, manakala bagi produk yang
dikeringkan dengan oven, komponen S dan N tidak konsisten sehingga 12 minggu
penynnpanan.
CHAPTER l
GENERAL INTRODUCTION
Durian (Durio zibethinus Murr) is a popular seasonal fruit grown in many
parts of South-East Asia and believed to be a native of Borneo island. The fruit has a
special taste, strong and indescribeable aroma, and is always dubbed as king of all
fiuits. Undoubtedly, durian is highly prized in the region, with Thailand, Malaysia and
Indonesia are major producers of this fruit in the world. Durian production and its
planted area in the three countries have shown a steady increase over the years.
Today, durians are not only planted in home garden but are also grown commercially
in large-scale plantation to meet the local and export demands (Tarmizi and Abidin,
1991).
The bulk of the durian fruit is mainly for fresh consumption. The edible
portion (aril) emanates a very strong odour much liked by the people in the region.
Normally, the fruits are allowed to mature and develop their full flavour on the tree
and collected after they fall to the ground. Durians are eaten shortly after harvest in
fresh form as it quickly turns sour and rancid due to some chemical changes that
follow. To a lesser extend, durian is processed into products like lempuk (durian
cake), durian-flavoured dodol and tempoyak (fermented durian aril).
111ese traditional products, llOwever, are not commercially produced in large
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quantities (Faridah et aI., 1982). Presently, some products manufactured from durian
such as candy, durian powder and durian flavour can be also found in the market.
Fruit leather is the term used for the products prepared by dehydration of:fruit
puree (Raab and Oehler, 1976). It is an established product, particularly in the North
American and European markets; however, it is a relatively unknown product in
Malaysia. The drying of fruit to make rolls or leathers offers a convenient method of
marketing fruit that would be unacceptable for the fresh fruit market (Steele, 1987).
Fruit leathers can be made from wide variety of fruits such as apple, apricot, banana,
cherry, grape, peach, pear, pineapple, plum, raspberry, strawberry, papaya, sweet
potato, ciku and jack fruit (Chauhan et al., 1993; Lodge, 1981; Chan and Cavaletto,
1978; Che Man and Raya, 1983; Che Man et a1., 1992; Che Man and Taufik, 1995;
Ahmed and Choudhary, 1995).
The consumer trend nowadays is to look for more natural snack foods.
Today, the consumers are more aware of what kind of food they are eating and with a
greater buying power, they tend to be choosy in terms of nutrition and safety.
Confectionary like sweets and candies, made from high amount of sugar, has very
little nutrition and could cause cavity among children. Fruit leather, which is made
from fruit, can be an alternative confectionary not only to children but also to adults.
Being made from natural fruits, fruit leather has all the goodness and nutrients of
fruits in it. Therefore, the development of a new fruit leather from durian could be an
alternative to increase the commercial value of durian, particularly when there is an
over production of the fruit during a season.
