UNIVERSITI PUTRA MALAYSIA

NURUL HANISAH JUHARI

FSTM 2012 6

EFFECTS OF HOT-AIR DRYING ON PHYSICOCHEMICAL CHARACTERISTICS, FLAVOUR PROFILES AND SENSORY ACCEPTANCE OF Citrus hystrix AND

Etlingera elatior Jack

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EFFECTS OF HOT-AIR DRYING ON PHYSICOCHEMICAL CHARACTERISTICS, FLAVOUR PROFILES AND SENSORY ACCEPTANCE OF Citrus hystrix AND

Etlingera elatior Jack

By

NURUL HANISAH JUHARI

Thesis Submitted to the School of Graduate Studies, Universiti Putra Malaysia, in Fulfillment of the Requirements for the Degree of Master of Science

June 2012

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Especially dedicated to my beloved parents, my family and also my husband. Thank you for your unconditional support with my studies. Thank you for believing in me; for allowing me to

further my studies. Please do not ever doubt my dedication. I love you.

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Abstract of thesis presented to the Senate of Universiti Putra Malaysia in fulfillment of the requirement for the degree of Master of Science

EFFECTS OF HOT-AIR DRYING ON THE PHYSICOCHEMICAL CHARACTERISTICS, FLAVOUR PROFILES AND SENSORY ACCEPTANCE OF

Citrus hystrix AND Etlingera elatior Jack

By

NURUL HANISAH JUHARI

June 2012

Chair: Associate Professor Lasekan Olusegun, PhD

Faculty: Food Science and Technology

Herbs and spices play important roles in Malay cuisine. The usage of kaffir lime (C. hystrix)

leaves and torch ginger (E. elatior) are not only limited to the addition of flavour and

enhancement of palatability of food but they also act as antioxidants. Both herbs were grown for

both flavouring and medicinal purposes. However, this herb is highly perishable in nature, have

short shelf life and deteriorate rapidly after harvesting that leads to loss of flavour and quality.

So, drying is an important technology for preserving the product quality and also preventing the

spoilage of the product during storage. Thus, this study was conducted to optimize the effects of

hot-air drying conditions (drying time, drying temperature and loading capacity) on

physicochemical characteristics (moisture content, water activity, texture and colour) of C.

hystrix and E. elatior that could be used for a high food grade spicing material. Secondly, the

flavour profiles of C. hystrix and E. elatior were determined between fresh and optimally dried

herbs. The herbs inclusion/infusion parameters levels (size, temperature and concentration of

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herbs) on sensory acceptance of Vichyssoise soup and sorbet were also optimized. The results

showed that the best response for torch ginger, within the range studied, was reached when the

drying time was 4.1 h, the drying temperature, 79 °C and loading capacity, 0.7 kg/m2

respectively. On the other hand, the overall optimum conditions that resulted in desirable dried

kaffir lime leaves, was achieved when the drying time was 4.9 h, the drying temperature, 60 °C

and loading capacity, 1.4 kg/m2. No significant (p>0.05) difference was found between the

experimental and predicted values, thus ensuring the adequacy of the response surface models

employed for describing the effects of hot-air drying on physicochemical properties of torch

ginger and kaffir lime leaves. At the second stage, liquid-liquid solvent extraction was employed

to extract flavour compounds of the samples which were analyzed using Gas Chromatography

(GC) and Gas Chromatography-Mass Spectrometry (GC-MS) with DB-5, BPX-5 as well as

Quadrex007CW columns. The finding from GC and GC-MS revealed that fresh torch ginger

contained 91 volatile compounds while optimally dried torch ginger contained 104 volatile

compounds using Quadrex007CW column. However, only 54 volatile compounds of fresh torch

ginger and 147 volatile compounds of optimally dried torch ginger were obtained using DB-5

column. The major aroma components in both fresh and optimally dried torch ginger were

alcohol, ester, alkane, carboxylic acid, ketone and aldehyde. A total of 45 compounds were

identified in fresh kaffir lime leaves as compared to 41 compounds in optimally dried kaffir lime

leaves using BPX-5 column. However, a total of 66 compounds were determined in fresh kaffir

lime leaves and 40 compounds in optimally dried kaffir lime leaves using DB-5 column.

Monoterpenes and sesquiterpenes were found to be major components. Finally, the herbs

inclusion/infusion parameters levels [size of herbs (2-100 mm), concentration of herbs (3-15 g/L)

and temperature of inclusion (25-100 °C)] in different types of food systems (liquid and semi

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solid) were determined. Sensory evaluations using 50 untrained panelists were utilized to assess

colour, aroma, taste and overall acceptability of products. The results from sensory evaluation

showed that vichyssoise soup flavoured with optimally dried C. hystrix leaves were more highly

preferred by panelist compared to vichyssoise soup flavoured with optimally dried E. elatior

while sorbet flavoured with optimally dried C. hystrix were highly preferred by panelist

compared to sorbet flavoured with optimally dried E. elatior. This study has significantly

contributed to the establishment of standardized measurements for the amount of herbs required

for various kinds of foods. Potentially, this study also yields herbs that reaches international

specification standard and enables worldwide export of Malaysian herbs.

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Abstrak tesis yang dikemukakan kepada Senat Universiti Putra Malaysia sebagai memenuhi keperluan untuk Ijazah Master Sains

KESAN PENGERINGAN UDARA PANAS KE ATAS CIRI-CIRI FIZIKOKIMIA, PROFIL PERISA DAN PENERIMAAN SENSORI BAGI

Citrus hysrix DAN Etlingera elatior Jack

Oleh

NURUL HANISAH JUHARI

Jun 2012

Pengerusi: Prof. Madya Lasekan Olusegun, PhD

Fakulti: Sains dan Teknologi Makanan

Herba dan rempah memainkan peranan penting dalam hidangan Melayu. Penggunaan daun limau

purut (C. hystrix) dan bunga kantan (E. elatior) tidak hanya terhad kepada tambahan perasa dan

peningkatan kesedapan makanan tetapi juga bertindak sebagai antioksidan. Kedua-dua herba ini

ditanam untuk kegunaan perasa makanan dan perubatan. Bagaimanapun, herba ini amat mudah

rosak di alam semula jadi, mempunyai tempoh simpanan yang pendek dan rosak dengan cepat

selepas menuai yang membawa kepada kehilangan perasa dan kualiti. Jadi, pengeringan ialah

satu teknologi penting untuk mengekalkan kualiti produk dan juga mencegah kerosakan produk

semasa penyimpanan. Oleh itu, kajian ini dijalankan untuk mengoptimumkan keadaan

pengeringan udara panas (masa pengeringan, suhu pengeringan dan kapasiti pembebanan) ke

atas ciri-ciri fizikokimia daun limau purut dan bunga kantan yang boleh digunakan sebagai

bahan rempah makanan bergred tinggi. Kedua, profil perasa telah ditentukan diantara herba yang

segar dengan herba yang telah dikeringkan secara optimum. Tahap-tahap parameter kemasukan

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herba optimum (saiz, suhu dan kepekatan herba) ke atas penerimaan sensori sup Vichyssoisse

dan ‘sorbet’ juga telah ditentukan. Keputusan menunjukkan respon yang terbaik untuk bunga

kantan, dalam julat yang dikaji, telah dicapai apabila masa pengeringan ialah 4.1 j, suhu

pengeringan, 79 °C dan kapasiti pembebanan, 0.7 kg/m2 masing-masing. Sebaliknya, keadaan

pengeringan optimum yang menyeluruh bagi daun limau purut, telah dicapai apabila masa

pengeringan ialah 4.9 j, suhu pengeringan, 60 °C dan kapasiti pembebanan, 1.4 kg/m2. Tiada

perbezaan yang signifikan (p>0.05) telah didapati antara nilai percubaan dan nilai ramalan,

demikian menjamin kecukupan model permukaan gerak balas yang telah diguna untuk

menggambarkan kesan pengeringan udara panas ke atas ciri-ciri fizikokimia bunga kantan dan

daun limau purut. Pada peringkat kedua, pengekstrakan pelarut cecair-cecair digunakan untuk

menganalisis sebatian perasa menggunakan Kromatografi Gas (GC) dan Kromatografi Gas-

Spektrometri Jisim (GC-MS) dengan menggunakan lajur DB-5, BPX-5 dan Quadrex007CW.

Penemuan dari GC and GC-MS mendedahkan bahawa bunga kantan segar mengandungi 91

sebatian mudah meruap berbanding bunga kantan yang dikeringkan secara optimum yang

mengandungi 104 sebatian mudah meruap setelah menggunakan lajur Quadrex007CW. Walau

bagaimanapun, terdapat hanya 54 sebatian mudah meruap bagi bunga kantan segar dan 147

sebatian mudah meruap bagi bunga kantan yang dikeringkan secara optimum setelah

menggunakan lajur DB-5. Komponen-komponen aroma utama dalam kedua-dua bunga kantan

segar dan juga bunga kantan yang dikeringkan secara optimum ialah alkohol, ester, alkana, asid

karboksilik, keton dan aldehid. Sejumlah 45 sebatian telah dikenal pasti dalam daun limau purut

yang segar berbanding 41 sebatian dalam daun limau purut yang dikeringkan secara optimum

setelah menggunakan lajur BPX-5. Walau bagaimanapun, sejumlah 66 sebatian telah ditentukan

untuk daun limau purut yang segar dan 40 sebatian untuk bunga kantan yang dikeringkan secara

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optimum setelah menggunakan lajur DB-5. Monoterpena and sesquiterpena telah didapati

sebagai komponen utama. Akhirnya, tahap-tahap kemasukan herba optimum [saiz herba (2-100

mm), kepekatan herba (3-15 g/L) dan suhu kemasukan (25-100 °C)] ke dalam sistem makanan

yang berbeza (cecair dan separuh pepejal) telah ditentukan. Penilaian deria menggunakan 50 ahli

panel tidak terlatih telah digunakan untuk menilai rupa, aroma, rasa dan kebolehterimaan

menyeluruh produk. Hasil daripada penilaian sensori menunjukkan bahawa sup vichyssoise

berperisa limau purut lebih diterima oleh ahli panel berbanding sup vichyssoise berperisa bunga

kantan manakala sorbet berperisa limau purut juga lebih digemari oleh ahli panel berbanding

sorbet berperisa bunga kantan. Kajian ini berupaya menyumbang secara signifikan kepada

pembentukan piawaian ukuran jumlah untuk herba ke dalam pelbagai jenis makanan. Kajian ini

juga berpotensi untuk menghasilkan herba yang telah dikering setanding spesifikasi antarabangsa

dan membolehkan herba-herba Malaysia dieksport ke seluruh dunia.

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ACKNOWLEDGEMENTS

Syukur Alhamdulillah to the Almighty Allah S.W.T for giving me strength, patience and

capability to complete this project and thesis write up.

First and foremost, I would like to express my infinite thanks and sincere appreciation to my

supervisor, Assoc. Prof. Dr. Lasekan Olusegun and my co-supervisors, Assoc. Prof. Dr. Sharifah

Kharidah Syed Muhammad and Assoc. Prof. Dr. Muhammad Shahrim Ab Karim for their

greatest guidance, useful suggestion, invaluable advice and encouragement in accomplishing this

project.

Apart from that, I would like to thank all lectures and staff from Faculty of Food Science and

Technology for their invaluable suggestions and constructive comments in my thesis project.

Also, huge thanks go to Ministry of Higher Education (MOHE) Malaysia for awarded SLAB

scholarship for me to pursue my Master of Science Degree in Food Science in Universiti Putra

Malaysia.

Moreover, I would like to express my warmest appreciation to my beloved parents and family for

their support and understanding of my difficulties to finish up my thesis.

Last but not least, I would like to express thousand thanks to my colleagues, who have been

directly or indirectly helping me to complete this project successfully.

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I certify that a Thesis Examination Committee has met on 11 June 2012 to conduct the final examination of Nurul Hanisah Juhari on her thesis entitled “Effect of Hot-air Drying on Physicochemical Characteristics, Flavour Profiles and Sensory Acceptances of Citrus hystrix and Etlingera elatior Jack” in accordance with the Universities and University Colleges Act 1971 and the Constitution of the Universiti Putra Malaysia [P.U.(A) 106] 15 March 1998. The committee recommends that the student be awarded the Master of Science.

Members of the Thesis Examination Committee were as follows:

Nor Ainy Mahyudin, PhD Senior Lecturer Faculty of Food Science and Technology University Putra Malaysia (Chairman) Alfi Khatib, PhD Associate Professor Faculty of Food Science and Technology University Putra Malaysia (Internal Examiner) Roselina Karim, PhD Associate Professor Faculty of Food Science and Technology University Putra Malaysia (Internal Examiner) Nor Azah Mohamad Ali, PhD Senior Research Officer Medicinal Plants Division Forest Research Institute Malaysia (External Examiner) ________________________________ SEOW HENG FONG, PhD Professor and Deputy Dean School of Graduate Studies Universiti Putra Malaysia Date: 27 September 2012

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This thesis was submitted to the Senate of university Putra Malaysia and has been accepted as fulfillment of the requirement for the degree of Master of Science. The members of the Supervisory Committee were as follows:

Lasekan Olusegun, PhD Associate Professor Faculty of Food Science and Technology Universiti Putra Malaysia (Chairman) Sharifah Kharidah Syed Muhammad, PhD Associate Professor Faculty of Food Science and Technology Universiti Putra Malaysia (Member) Muhammad Shahrim Ab Karim, PhD Associate Professor Faculty of Food Science and Technology Universiti Putra Malaysia (Member) ______________________________ BUJANG BIN KIM HUAT, PhD

Professor and Dean School of Graduate Studies Universiti Putra Malaysia

Date: 27 September 2012

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DECLARATION

I declare that the thesis is my original work except for quotations and citations which have been duly acknowledged. I also declare that it has not been previously, and is not concurrently, submitted for any other degree at Universiti Putra Malaysia or at any other institution.

_____________________________

NURUL HANISAH JUHARI

Date: 11 June 2012

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LIST OF TABLES

Table Page

2.1 A conventional classification of spices is based on degree 5 of taste

2.2 Definition and examples of spices and culinary herbs 6

2.3 Cooking factors that influence spice flavours and some 9 functions of spice Methods used for drying of foodstuffs

2.4 Guidelines to check for freshness of herbs and spices 11

2.5 Volatile compound classes and their sensory characteristic 20

2.6 Methods used for drying of foodstuffs 21

2.7 Previous literature on different drying methods 24

2.8 Types of moist-heat methods 31

3.1 Levels of independent variables for hot-air oven drying 41 established according to the central composite design (CCD) for

dried E. elatior

3.2 Levels of independent variable for hot-air oven drying 41 established according to the central composite design (CCD) for dried C. hystrix leaves

3.3 The matrix of central composite design (CCD) for dried E. elatior 41

3.4 The matrix of central composite design (CCD) for dried C. hystrix leaves 42

3.5 The matrix of central composite design (CCD) and experimental data 48 obtained for the response variables studied (Y1-6) (mean±SD) for dried E. elatior

3.6 Regression summary and analysis of variance for moisture 49 content, water activity, texture, colour-L, colour-a and colour-b in uncoded form of process variable for dried E. elatior

3.7 ANOVA and regression coefficients of the first- and 50 second-order polynomial models for dried E. elatior

3.8 Experimental and predicted values for the response variables 62 studied for dried E. elatior

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3.9 The matrix of central composite design (CCD) and experimental 65 data obtained for the response variables studied (Y1-6) (mean±SD) for dried C. hystrix leaves

3.10 Regression summary and analysis of variance for moisture 66 content, water activity, texture, colour-L, colour-a and colour-b in uncoded form of process variable for dried C. hystrix leaves

3.11 ANOVA and regression coefficients of the first- and 67

second-order polynomial models for dried C. hystrix leaves

3.12 Experimental and predicted values for the response variables 79 studied for dried C. hystrix leaves

4.1 Characteristics of the calibration curves 91

4.2 Performance characteristics of the calibration curves 92

4.3 Volatile constituents of fresh C. hystrix leaves using BPX–5 column 96

4.4 Volatile constituents of optimally dried C. hystrix leaves using 98

BPX-5 column

4.5 Volatile constituents of fresh C. hystrix leaves using DB-5 column 103

4.6 Volatile constituents of optimally dried C. hystrix leaves using 105 DB-5 column

4.7 Volatile constituents of fresh E. elatior using QUADREX-007CW 111 column

4.8 Volatile constituents of optimally dried E. elatior using 114 QUADREX-007CW column

4.9 Volatile constituents of fresh E. elatior using DB-5 column 123

4.10 Volatile constituents of optimally dried E. elatior using DB-5 124 column

5.1 Ingredients of Vichyssoise Soup 133

5.2 Ingredients of Basic Sorbet 134

5.3 Levels of independent variables for vichyssoise soup established 136

according to the central composite design (CCD) for optimally dried E. elatior

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5.4 Levels of independent variables for vichyssoise soup established 136 according to the central composite design (CCD) for optimally dried C. hystrix leaves

5.5 Levels of independent variables for sorbet established according 137 to the central composite design (CCD) for optimally dried E. elatior

5.6 Levels of independent variables for sorbet established according 137 to the central composite design (CCD) for optimally dried C. hystrix leaves

5.7 The matrix of central composite design (CCD) for vichyssoise soup 137 flavoured with optimally dried E. elatior

5.8 The matrix of central composite design (CCD) for vichyssoise 138 soup flavoured with optimally dried C. hystrix leaves

5.9 The matrix of central composite design (CCD) for sorbet flavoured 139 with optimally dried E. elatior

5.10 The matrix of central composite design (CCD) for sorbet flavoured 140 with optimally dried C. hystrix leaves.

5.11 The matrix of central composite design (CCD) and experimental data 144 obtained for the response variables studied (Y1-4) (mean±SD) for vichyssoise soup flavoured with optimally dried E. elatior.

5.12 Regression summary and analysis of variance for appearance, 145 aroma, taste and overall acceptability in uncoded form of process variablefor vichyssoise soup flavoured with optimally dried E. elatior

5.13 ANOVA and regression coefficients of the first- and second-order 146 polynomial models for vichyssoise soup flavoured with optimally dried E. elatior

5.14 Experimental and predicted values for the response variables 156 studied for vichyssoise soup flavoured with optimally dried E. elatior

5.15 The matrix of central composite design (CCD) and experimental 159 data obtained for the response variables studied (Y1-4) (mean±SD) for vichyssoise soup flavoured with optimally dried C. hystrix leaves

5.16 Regression summary and analysis of variance for appearance, 160 aroma, taste and overall acceptability in uncoded form of process

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variable for vichyssoise soup flavoured with optimally dried C. hystrix leaves

5.17 ANOVA and regression coefficients of the first- and second-order 161 polynomial models for vichyssoise soup flavoured with optimally dried C. hystrix leaves

5.18 Experimental and predicted values for the response variables 169 studied for vichyssoise soup flavoured with optimally dried C. hystrix leaves

5.19 The matrix of central composite design (CCD) and experimental 172 data obtained for the response variables studied (Y1-4) (mean±SD) for sorbet flavoured with optimally dried E. elatior

5.20 Regression summary and analysis of variance for appearance, 173 aroma, taste and overall acceptability in uncoded form of process variable for sorbet flavoured with optimally dried E. elatior

5.21 ANOVA and regression coefficients of the first- and second-order 174 polynomial models for sorbet flavoured with optimally dried E. elatior

5.22 Experimental and predicted values for the response variables 184 studied for sorbet flavoured with optimally dried E. elatior

5.23 The matrix of central composite design (CCD) and experimental 187 data obtained for the response variables studied (Y1-4) (mean±SD) for sorbet flavoured with optimally dried C. hystrix leaves

5.24 Regression summary and analysis of variance for appearance, 188 aroma, taste and overall acceptability in uncoded form of process variable for sorbet flavoured with optimally dried C. hystrix leaves

5.25 ANOVA and regression coefficients of the first- and second-order 189 polynomial models for sorbet flavoured with optimally dried C. hystrix leaves

5.26 Experimental and predicted values for the response variables 198 studied for sorbet flavoured with optimally dried C. hystrix leaves

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LIST OF FIGURES

Figure Page

2.1 Kaffir lime leaf (Citrus hystrix) 13

2.2 Torch ginger (Etlingera elatior) 15

3.1 Response surface plot for effect of hot-air drying conditions (drying time, 51 drying temperature and loading capacity) on the moisture content of E. elatior (a. drying time vs drying temperature, b. drying time vs loading capacity, c. drying temperature vs loading capacity)

3.2 Response surface plot for effect of hot-air drying conditions 54 (drying temperature and loading capacity) on the water activity of dried E. elatior

3.3 Response surface plot for effect of hot-air drying conditions 55 (drying temperature and loading capacity) on the texture of dried E. elatior

3.4 Response surface plot for effect of hot-air drying conditions 57 (drying temperature and loading capacity) on the colour-L of dried E. elatior

3.5 Response surface plot for effect of hot-air drying (drying time, drying 59 temperature and loading capacity) on the colour-a of E. elatior. (a. drying time vs drying temperature, b. drying time vs loading capacity, c. drying temperature vs loading capacity)

3.6 Response surface plot for effect of hot-air drying conditions (drying 68 time and drying temperature) on the moisture content of dried C. hystrix leaves

3.7 Response surface plot for effect of hot-air drying conditions (drying 70 time and drying temperature) on the water activity of dried C. hystrix leaves

3.8 Response surface plot for effect of hot-air drying conditions (drying 71 time and drying temperature) on the texture of dried C. hystrix leaves

3.9 Response surface plot for effect of hot-air drying conditions (drying time, 73 drying temperature and loading capacity) on the colour-L of dried C. hystrix leaves (a.drying time vs drying temperature, b. drying time vs loading capacity, c. drying temperature vs loading capacity)

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3.10 Response surface plot for effect of hot-air drying conditions (drying time, 75 drying temperature and loading capacity) on the colour-a of dried C. hystrix leaves (a. drying time vs drying temperature, b. drying time vs loading capacity, c. drying temperature vs loading capacity)

3.11 Response surface plot for effect of hot-air drying conditions (drying 77 time and loading capacity) on the colour-b of dried C. hystrix leaves

5.1 Response surface plot for effect of different herbs inclusion levels 147 (size of herbs, concentration of herbs and temperature of inclusion) on appearance score of vichyssoise soup flavoured with optimally dried E. elatior (a. size of herbs vs concentration of herbs, b. size of herbs vs temperature of inclusion, c. concentration of herbs vs temperature of inclusion).

5.2 Response surface plot for effect of different herbs inclusion levels 151 (size of herbs, concentration of herbs and temperature of inclusion) on taste score of vichyssoise soup flavoured with optimally dried E. elatior (a. size of herbs vs concentration of herbs, b. size of herbs vs temperature of inclusion, c. concentration of herbs vs temperature of inclusion)

5.3 Response surface plot for effect of different herbs inclusion levels 153 (size of herbs, concentration of herbs and temperature of inclusion) on overall acceptability score of vichyssoise soup flavoured with optimally dried E. elatior (a. size of herbs vs concentration of herbs, b. size of herbs vs temperature of inclusion, c. concentration of herbs vs temperature of inclusion)

5.4 Response surface plot for effect of different herbs inclusion levels 162 (size of herbs and temperature of inclusion) on appearance score of vichyssoise soup flavoured with optimally dried C. hystrix leaves

5.5 Response surface plot for effect of different herbs inclusion levels 175 (size of herbs and concentration of herbs) on appearance of sorbet flavoured with optimally dried E. elatior

5.6 Response surface plot for effect of different herbs inclusion levels 179 (size of herbs, concentration of herbs and temperature of infusion) on taste score of sorbet flavoured with optimally dried E. elatior (a. saiz of herbs vs concentration of herbs, b. saiz of herbs vs temperature of infusion, c. concentration of herbs vs temperature of infusion)

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5.7 Response surface plot for effect of different herbs inclusion levels 181 (concentration of herbs and temperature of infusion) on overall acceptability score of sorbet flavoured with optimally dried E. elatior

5.8 Response surface plot for effect of different herbs inclusion levels 190 (size of herbs, concentration of herbs and temperature of infusion) on appearance score of sorbet flavoured with optimally dried C. hystrix leaves. (a. size of herbs vs concentration of herbs, b. size of herbs vs temperature of infusion, c. concentration of herbs vs temperature of infusion)

5.9 Response surface plot for effect of different herbs inclusion levels 192 (size of herbs and temperature of infusion) on aroma score of sorbet flavoured with optimally dried C. hystrix leaves

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LIST OF APPENDICES

Appendix Page

A Sensory Evaluation form for Vichyssoise Soup [Cream of Potato 217 & Leek Soup flavoured with Torch ginger (Bunga Kantan)] B Sensory Evaluation form for Vichyssoise Soup [Cream of Potato 221 & Leek Soup flavoured with Kaffir lime leaves (Daun limau purut)] C Sensory Evaluation form for Sorbet flavoured with Torch ginger 225 (Bunga Kantan) D Sensory Evaluation form for Sorbet flavoured with Kaffir lime leaves 229 (Daun limau purut) �

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LIST OF ABBREVIATIONS

AIA Acid Insoluble Ash

amu Atomic mass unit

ANOVA Analysis of Variance

AOAC Association of Analytical Chemists

ASTA American Spice Trade Association

Aw Water activity

°C Celsius

cm Centimeter

CCD Central Composite Design

eV Electronvolt

ESA European Standard Association

Eq. Equation

g Gram

GC Gac chromatography

GC-MS Gas Chromatography – Mass Spectrometry

HCl Hydrochloric acid

hr Hour

ICMSF International Commision on Microbiological Specifications for Foods

ISO International Standard Organization

kg Kilogram

LD Loss on drying

LOD Limit of detection

LOL on-line linearity

LOQ Limit of quantification

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min Minute

m2 Meter square

mg Milligram

mm Millimeter

µm Micrometer

µl Micro liter

MS Mass – Spectrometry

N morality

NIST National Institute of Standards and Technology

R2 Coefficient of determination

RSD Relative standard deviation

RSM Response surface methodology

SD Standard deviation

SDE Simultaneous Distillation - Extraction

V/O Volatile oil

W Watt

wt Weight

w/w Weight per weight

3D Three-dimensional

% Percentage

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TABLE OF CONTENTS

Page

DEDICATION ii ABSTRACT iii ABSTRAK vi ACKNOWLEDGEMENTS ix APPROVAL x DECLARATION xii LIST OF TABLES xiii LIST OF FIGURES xvii LIST OF APPENDICES xx LIST OF ABBREVIATIONS xxi CHAPTER

1 INTRODUCTION 1

2 LITERATURE REVIEW 2.1 Herbs and Spices 5

2.1.1 Definition of Spices 5 2.1.2 Basic Uses for Spices 6 2.1.3 Spices Qualities and Specification 7 2.1.4 The Effect of Cooking on Spice Flavours and 9 Functions 2.1.5 Adding Herbs and Spices to Food 10 2.1.6 Forms of Spices 10 2.1.7 Storage and Shelf life of Herbs and Spices 10

2.2 Spices, Flavourings and Seasonings of Popular Authentic 12 Ethnic

2.3 Kaffir lime leaves (Citrus hystrix) 13 2.4 Torch ginger (Etlingera elatior) 15 2.5 Flavour Profiles of C. hystrix and E. elatior 17

2.5.1 Chemical Compounds Responsible for Flavour 20 2.6 Drying of Herbs and Spices 20

2.6.1 Methods of Drying 21 2.6.2 The Effects of Drying on Aromatic Spices 29

2.7 Application of Herbs into Food System 30 2.8 Cooking Methods 30 2.9 The Art of Flavouring 31

2.9.1 Basic Rules of Flavouring 32

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2.9.2 When to Flavour 32 2.9.3 Preliminary Cooking and Flavouring 32

3 OPTIMIZATION OF HOT-AIR DRYING CONDITIONS ON

THE PHYSICOCHEMICAL CHARACTERISTICS OF Citrus hystrix AND Etlingera elatior 3.1 Introduction 33 3.2 Materials and Methods 35

3.2.1 Sample Preparation 35 3.2.2 Drying Equipment 36 3.2.3 Drying Procedure 36 3.2.4 Physicochemical Analysis 37

3.2.4.1 Determination of moisture content 37 3.2.4.2 Determination of water activity 37 3.2.4.3 Determination of texture (brittleness) 38 3.2.4.4 Determination of colour (L, a, b) 38

3.2.5 Experimental Design and Data Analysis 39 3.2.6 Statistical Analysis 41 3.2.7 Optimization Procedure 42 3.2.8 Verification of Models 43

3.3 Results and Discussion 3.3.1 Torch ginger (Etlingera elatior Jack) 44

3.3.1.1 Fitting the response surface models 44 3.3.1.2 Moisture content 50 3.3.1.3 Water activity 53 3.3.1.4 Texture (brittleness) 54 3.3.1.5 Colour-L 56 3.3.1.6 Colour-a 58 3.3.1.7 Optimization and validation procedures 60

3.3.2 Kaffir lime leaves (Citrus hysrix) 62 3.3.2.1 Fitting the response surface models 62 3.3.2.2 Moisture content 67 3.3.2.3 Water activity 69 3.3.2.4 Texture (brittleness) 70 3.3.2.5 Colour-L 72 3.3.2.6 Colour-a 74 3.3.2.7 Colour-b 76 3.3.2.8 Optimization and validation procedures 77

3.4 Conclusion 79

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4 EFFECT OF HOT-AIR DRYING CONDITIONS ON THE FLAVOUR VOLATILES OF Citrus hystrix AND Etlingera elatior 4.1 Introduction 80 4.2 Materials and Methods 82

4.2.1 Sample Preparation 82 4.2.2 Drying Equipment and Drying Procedures 83 4.2.3 Chemicals Standards and Reagents 83 4.2.4 Extraction and Concentration of Volatiles Compounds 84 4.2.5 Chromatographic Analysis of the Volatiles Compounds 85

4.2.5.1 Gas Chromatography 85 4.2.5.2 Gas Chromatography – Mass Spectrometry 86

4.2.6 Identification of the Essential Oils Compounds 88 4.2.7 Quantification 88

4.3 Results and Discussion 89 4.3.1 Performance Characteristic 89

4.3.1.1 Calibration and Linearity 89 4.3.1.2 Detection and Quantification Limits, 89

Recovery and Analytical Sensitivity 4.3.2 Determination of Flavour Volatiles Compounds in 91

Fresh and Optimally Dried Citrus hystrix leaves 4.3.3 Determination of Flavour Volatiles Compounds in 106

Fresh and Optimally Dried Etlingera elatior Jack 4.4 Conclusion 129

5 OPTIMIZATION THE HERBS INCLUSION/INFUSION PARAMETERS

LEVELS OF Citrus hystrix AND Etlingera elatior ON SENSORY ACCEPTANCE OF VICHYSSOISE SOUP AND SORBET 5.1 Introduction 130 5.2 Materials and Methods 131

5.2.1 Sample Preparation 131 5.2.2 Basic Vichyssoise Soup Formulation 132

5.2.2.1 Preparation of Vichyssoise Soup 132 5.2.3 Basic Sorbet Formulation 133

5.2.3.1 Preparation of Sorbet 133 5.2.4 Sensory evaluation 134 5.2.5 Experimental Design and Data Analysis 134 5.2.6 Statistical Analysis 140 5.2.7 Optimization Procedure 140 5.2.8 Verification of Models 140

5.3 Results and Discussion 140

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5.3.1 Vicyssoisse Soup [Cream of Potato & Leek Soup 140 flavoured with Optimally Dried Etlingera elatior Jack 5.3.1.1 Fitting the response surface models 140 5.3.1.2 Appearance 146 5.3.1.3 Aroma 148 5.3.1.4 Taste 150 5.3.1.5 Overall acceptability 152 5.3.1.6 Optimization and validation procedures 154

5.3.2 Vicyssoisse Soup [Cream of Potato & Leek Soup 156 flavoured with optimally dried Citrus hystrix leaves 5.3.2.1 Fitting the response surface models 156 5.3.2.2 Appearance 161 5.3.2.3 Aroma 163 5.3.2.4 Taste 164 5.3.2.5 Overall acceptability 165 5.3.2.6 Optimization and validation procedures 167

5.3.3 Sorbet flavoured with Optimally Dried Etlingera elatior Jack 169 5.3.3.1 Fitting the response surface models 169 5.3.3.2 Appearance 174 5.3.3.3 Aroma 176 5.3.3.4 Taste 178 5.3.3.5 Overall acceptability 180 5.3.3.6 Optimization and validation procedures 182

5.3.4 Sorbet flavoured with Optimally Dried Citrus hystrix 184 leaves 5.3.4.1 Fitting the response surface models 184 5.3.4.2 Appearance 189 5.3.4.3 Aroma 191 5.3.4.4 Taste 193 5.3.4.5 Overall acceptability 194 5.3.4.6 Optimization and validation procedures 196

5.4 Conclusion 198 6 GENERAL CONCLUSION AND RECOMMENDATIONS 201

FOR FUTURE RESEARCH

REFERENCES 203 APPENDICES 217 BIODATA OF STUDENT 233 LIST OF PUBLICATIONS 234

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