UNIVERSITI PUTRA MALAYSIA

EFFECTS OF MICROWAVE-VACUUM DRYING ON DRYING KINETICS AND QUALITY OF ORTHOSIPHON ARISTATUS (BLUME) MIQ. LEAVES

AND EURYCOMA LONGIFOLIA JACK ROOTS

HADA MASAYU ISMAIL @ DAHLAN

FK 2016 156

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HT UPMEFFECTS OF MICROWAVE-VACUUM DRYING ON DRYING KINETICS

AND QUALITY OF Orthosiphon aristatus (BLUME) MIQ. LEAVES AND Eurycoma longifolia JACK ROOTS

By

HADA MASAYU BINTI ISMAIL @ DAHLAN

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

November 2016

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COPYRIGHT All material contained within the thesis, including without limitation text, logos, icons, photographs and all other artwork, is copyright material of Universiti Putra Malaysia unless otherwise stated. Use may be made of any material contained within the thesis for non-commercial purposes from the copyright holder. Commercial use of material may only be made with the express, prior, written permission of Universiti Putra Malaysia. Copyright © Universiti Putra Malaysia

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DEDICATION

This thesis is specially dedicated to

my husband, parents, children

and

my late son who passed away on 17th June 2013

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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 MICROWAVE-VACUUM DRYING ON DRYING KINETICS

AND QUALITY OF Orthosiphon aristatus (BLUME) MIQ. LEAVES AND

Eurycoma longifolia JACK ROOTS

By

HADA MASAYU BINTI ISMAIL @ DAHLAN

November 2016

Chairman : Associate Professor Mohd. Nordin Ibrahim, PhD

Faculty : Engineering

Orthosiphon aristatus (OA) is known locally as misai kucing; belongs to the family

Lamiaceae. Previous studies have shown that the leaves of OA have beneficial effects

including anti-oxidant, anti-hypertensive and diuretic effect. Another herb, Eurycoma

longifolia (EL) is well-known for its local name as tongkat ali; belongs to the family

Simaroubaceae. Previous research has shown that the roots of EL have beneficial

effects including anti-malarial, anti-bacterial and anti-pyretic.

The presence of the properties that are beneficial in both herbs have shown that

extracts from these materials have great potential in the development of various

healthcare products. However, research in the area of processing for the production of

bioactive compounds still insufficient.

This research studied the effects of microwave-vacuum drying (MVD) techniques of

OA leaves and EL roots and determined the optimum drying condition based on drying

kinetics and phytochemicals content. Optimum condition of convection oven drying

obtained at 45°C for the leaves and 60°C for the roots were selected and used as the

control drying method in the study.

The MVD experimental runs and optimization work were designed using Central-

composite of Response Surface Methodology (RSM). Thirteen experiment points

were obtained from RSM with microwave-power ranged from 150 – 300 W and

vacuum pressure ranged from15 – 50 kPa. Experiments were carried out at continuous

and intermittent modes. The effects of the two variables on phytochemicals of OA

leaves and EL roots were investigated. Quality indicator selected for the leaves and

the roots were Rosmarinic acid (RA) and Eurycomanone (EUR), respectively. At

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intermittent mode, three pulsation ratio (PR) of 2, 3 and 4 were studied. Three thin-

layer drying models namely Page, Midili and Logarithmic were applied to fit the

experimental data in order to select the best model to represent MVD process for both

type of herbs.

The optimum MVD conditions at continuous mode for the highest RA content of OA

leaves were obtained at 300 W microwave power and 50 kPa vacuum pressure. The

optimum responses of the process were: RA 556.28 mg/L and drying time 17.14

minutes. Whereas for optimum MVD conditions at intermittent mode, PR 3 was found

to be the most suitable condition with 700.39 mg/L of RA concentration in the dried

leaves. On the other hand, for EL roots, the optimum MVD conditions at continuous

mode for the highest EUR content were obtained at 150 W microwave power and 50

kPa vacuum pressure. The optimum responses of the process were: EUR 7.92 mg/L

and drying time 18.64 minutes. Whereas for optimum MVD conditions at intermittent

mode, PR 4 was found to be the most suitable condition with 3.58 mg/L of EUR

concentration in the dried roots.

Midili model was found to be the most suitable model to describe the MVD process

of both types of herbs with root mean square error (RMSE) ranged from 0.9953 –

0.999 for OA leaves and 0.9666 – 0.999 for EL roots.

MVD at 300 W microwave power and 50 kPa vacuum pressure, at intermittent mode,

with PR 3 was found out to be the most suitable drying method for the microwave-

vacuum drying technique for OA leaves as it contained the highest amount of RA.

While, for EL roots, MVD at 150 W microwave power and 50 kPa vacuum pressure,

at continuous mode was found out to be the most suitable drying method for the

microwave-vacuum drying technique for EL roots however it contained less amount

of EUR as compared to EUR from control drying method.

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

KESAN PENGERINGAN SECARA VAKUM-GELOMBANG MIKRO TERHADAP KINETIK PENGERINGAN DAN KUALITI HERBA DAUN

Orthosiphon aristatus(BLUME) MIQ. DAN AKAR Eurycoma longifolia JACK

Oleh

HADA MASAYU BINTI ISMAIL @ DAHLAN

November 2016

Pengerusi : Profesor Madya Mohd. Nordin Ibrahim, PhD Fakulti : Kejuruteraan

Orthosiphon aristatus (OA) lebih dikenali dengan nama tempatannya misai kucing; tergolong dalam keluarga Lamiaceae. Kajian sebelum ini menunjukkan bahawa daun OA mempunyai kesan berfaedah termasuk anti-oksida, anti-hipertensi dan kesan diuretik.

Manakala Eurycoma longifolia (EL) pula terkenal dengan nama tempatannya tongkat ali; tergolong dalam keluarga Simaroubaceae. Kajian sebelum ini menunjukkan bahawa akar EL mempunyai kesan berfaedah termasuk anti-malaria, anti-bakteria dan anti-piretik.

Kehadiran sifat-sifat yang bermanfaat dalam kedua-dua herba ini menunjukkan bahawa ekstrak daun OA dan akar EL mempunyai potensi besar dalam pembangunan pelbagai produk kesihatan. Walaubagaimanapun, penyelidikan dalam aspek pemprosesan untuk penghasilan komponen bioaktifnya masih tidak mencukupi.

Objektif kajian ini adalah untuk mengkaji kesan teknik pengeringan secara vakum-gelombang mikro (MVD) pada herba daun OA dan akar EL, serta untuk menentukan kondisi pengeringan optimum berdasarkan kinetik pengeringan dan kandungan fitokimia herba tersebut. Kondisi optimum pengeringan secara oven konveksi yang diperolehi pada suhu 45°C untuk daun OA dan 60°C untuk akar EL telah dipilih dan digunakan sebagai kaedah kawalan di dalam penyelidikan ini.

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Jumlah eksperimen MVD dan kerja optimasasi telah direka menggunakan rekabentuk komposit-pusat daripada Metodologi Permukaan Respons (RSM). Tiga belas eksperimen telah diperolehi daripada RSM dengan kuasa gelombang mikro di antara 150 - 300 W dan tekanan vakum di antara 15 - 50 kPa. Eksperimen telah dijalankan pada mod berterusan dan tidak-berterusan. Kesan kedua-dua pembolehubah, iaitu kuasa gelombang mikro dan tekanan vakum, terhadap kandungan fitokimia daun OA dan akar EL telah dikaji. Petunjuk kualiti Asid rosmarinik (RA) dan Eurycomanone (EUR) telah dipilih masing-masing untuk daun OA dan akar EL. Bagi kajian yang melibatkan mod tidak-berterusan, tiga ratio (PR) telah dikaji iaitu ratio 2, 3 dan 4. Tiga model pengeringan iaitu Page, Midili dan Logarithmic telah digunakan untuk menyesuaikan data eksperimen bagi memilih model pengeringan yang terbaik untuk mewakili proses MVD kedua-dua jenis herba.

Kondisi optimum MVD pada mod berterusan telah diperolehi pada kuasa gelombang mikro 300 W dan 50 kPa tekanan vakum untuk daun OA. Pada kondisi ini, kandungan RA adalah yang tertinggi. Respons optimum yang diperolehi adalah: RA 556.28 mg / L dan masa pengeringan 17.14 minit. Manakala PR 3 didapati paling sesuai untuk kondisi optimum MVD pada mod tidak-berterusan, dengan kepekatan RA sebanyak 700.39 mg / L dalam daun OA. Sebaliknya, bagi akar EL, kondisi optimum MVD pada mod berterusan telah diperolehi pada kuasa gelombang mikro 150 W dan 50 kPa tekanan vakum. Pada kondisi ini, kandungan EUR adalah yang tertinggi. Respons optimum yang diperolehi adalah: EUR 7.92 mg / L dan masa pengeringan 18.64 minit. Manakala PR 4 didapati paling sesuai untuk kondisi optimum MVD pada mod tidak-berterusan, dengan kepekatan RA sebanyak 700.39 mg / L dalam akar EL.

Model pengeringan Midili didapati paling sesuai untuk menggambarkan proses MVD bagi kedua-dua jenis herba dengan purata-ralat-punca-kuasa (RMSE) antara 0.9953 - 0.999 untuk daun OA dan 0.9666 - 0.999 untuk akar EL.

Melalui kajian yang telah dijalankan ini, didapati kaedah pengeringan yang paling sesuai untuk daun OA menggunakan teknik MVD adalah pada kondisi pengeringan 300 W kuasa gelombang mikro dan 50 kPa tekanan vakum, pada mod tidak-berterusan, PR 3. Ini adalah kerana kepekatan RA adalah paling tinggi pada kondisi ini. Manakala, untuk akar EL, didapati kaedah pengeringan yang paling sesuai menggunakan teknik MVD adalah pada kondisi pengeringan 150 W kuasa gelombang mikro dan 50 kPa tekanan vakum, pada mod berterusan. Namun, kepekatan EUR yang diperolehi adalah kurang berbanding kaedah kawalan.

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ACKNOWLEDGEMENTS

Alhamdulillah, praise to Allah, the Lord of the world and to His final messenger, Prophet Muhammad S.A.W for the blessings and guidance given. Firstly, I would like to convey my acknowledgement towards my dissertation supervisor, Associate Professor Dr. Mohd. Nordin Ibrahim for his guidance, constructive comments and criticism, relentlessly advice and support that enabled me to understand and finish this study. I would like to thank my two co-supervisors, Dr. Pin Kar Yong, who cared so much about my work and responded to my questions and queries so promptly, and Dr. Rabitah Zakaria, for her fruitful discussions during my every-semester project presentation. I also would like to express my thanks to my immediate superior for his support at the place I currently working at, En. Mohd. Shahidan Mohamad Arshad. A big thank you to all those who have been here throughout most of my studies (Mohd. Farhan, Khairul Kamilah, Noor Rasyila, Saidatul Husni, Fauziah, Zamree, Sharmizi, Mohd. Sharul Nizam and Dr. Fadzureena). I would like to give my utmost appreciation to my mother who has instilled in me the value of education in life, as well as my husband who always given me full support and encouragement during my study at Universiti Putra Malaysia. Finally, for others who I did not mentioned above that have help and contribute in this study directly or indirectly. I appreciate it very much and would like to give my thanks to all of you from every effort given. Finally, the good comes from Allah and the bad come from my own weakness. Hopefully my efforts would be benefited by others and used for the good will. Insya Allah.

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

Mohd. Nordin Ibrahim, PhD Associate Professor Faculty of Engineering Universiti Putra Malaysia (Chairman)

Rabitah Zakaria, PhD Senior Lecturer Faculty of Engineering Universiti Putra Malaysia (Member)

Pin Kar Yong, PhD Research Officer Herbal Technology Centre Innovation and Commercialisation Division Forest Research Institute Malaysia (Member)

ROBIAH BINTI YUNUS, PhD Professor and Dean School of Graduate Studies Universiti Putra Malaysia

Date:

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Declaration by graduate student

I hereby confirm that: this thesis is my original work; quotations, illustrations and citations have been duly referenced; this thesis has not been submitted previously or concurrently for any other degree

at any institutions; intellectual property from the thesis and copyright of thesis are fully-owned by

Universiti Putra Malaysia, as according to the Universiti Putra Malaysia(Research) Rules 2012;

written permission must be obtained from supervisor and the office of DeputyVice-Chancellor (Research and innovation) before thesis is published (in the formof written, printed or in electronic form) including books, journals, modules,proceedings, popular writings, seminar papers, manuscripts, posters, reports,lecture notes, learning modules or any other materials as stated in the UniversitiPutra Malaysia (Research) Rules 2012;

there is no plagiarism or data falsification/fabrication in the thesis, and scholarlyintegrity is upheld as according to the Universiti Putra Malaysia (GraduateStudies) Rules 2003 (Revision 2012-2013) and the Universiti Putra Malaysia(Research) Rules 2012. The thesis has undergone plagiarism detection software

Signature: ________________________________ Date: __________________

Name and Matric No: Hada Masayu Binti Ismail @ Dahlan, GS28891

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Declaration by Members of Supervisory Committee This is to confirm that: the research conducted and the writing of this thesis was under our supervision; supervision responsibilities as stated in the Universiti Putra Malaysia (Graduate

Studies) Rules 2003 (Revision 2012-2013) were adhered to.

Signature: Name of Chairman of Supervisory Committee:

Associate Professor Dr. Mohd. Nordin Ibrahim

Signature:

Name of Member of Supervisory Committee:

Dr. Rabitah Zakaria

Signature:

Name of Member of Supervisory Committee:

Dr. Pin Kar Yong

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TABLE OF CONTENTS Page ABSTRACT iABSTRAK iiiACKNOWLEDGEMENTS vAPPROVAL viDECLARATION viiiLIST OF TABLES xiiiLIST OF FIGURES xvLIST OF ABBREVIATIONS xviii

CHAPTER 1 INTRODUCTION 1 1.1 Herbal industry in Malaysia 1 1.2 Herbal postharvest processing 1 1.3 Problem statements 2 1.4 Objectives 3 1.5 Scope of research 3 1.6 Structure of the thesis 3 2 LITERATURE REVIEW 5 2.1 Orthosiphon aristatus (OA) 5 2.1.1 Traditional uses and beneficial bioactivity of OA

leaves 5

2.1.2 Rosmarinic acid (RA) in OA leaves 6 2.1.3 Safety of OA leaves 7 2.2 Eurycoma longifolia Jack (EL) 7 2.2.1 Traditional Uses and beneficial bioactivity of EL

Roots 7

2.2.2 Eurycomanone (EUR) in EL Roots 9 2.2.3 Safety of EL Roots 10 2.3 Drying 10 2.3.1 Convective drying 12 2.3.2 Microwave-vacuum drying 15 2.4 Response surface methodology (RSM) 18 3 METHODOLOGY 21 3.1 Introduction 21 3.2 Materials 21 3.2.1 Orthosiphon aristatus leaves 21 3.2.2 Eurycoma longifolia roots 23 3.3 Equipments Setup 23 3.4 Experimental Design 25 3.4.1 Continuous MVD 25 3.4.2 Intermittent MVD 26 3.4.3 Convection oven drying 27

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3.5 Qualitative and Quantitative Determination of phytochemicals in dried materials

28

3.5.1 Orthosiphon aristatus 28 3.5.2 Eurycoma longifolia 29 3.5.3 Preparation of crude extract 29 3.6 Data Analyses 30 3.6.1 Drying Curve 30 3.6.2 Drying rate curve 30 3.6.3 Curves fitting 30 3.6.4 Phytochemicals Qualitative and Quantitative

Analysis 31

3.6.5 Optimisation Using Response Surface Methodology (RSM)

31

3.7 Statistical Analysis 32 4 RESULTS AND DISCUSSION 33 4.1 Convection Oven Drying of Orthosiphon aristatus (OA)

Leaves 33

4.1.1 Drying Kinetic of OA leaves from Convection Oven Drying

33

4.1.2 Phytochemical content of OA Leaves from Convection Oven Drying

34

4.1.3 Curve Fitting of Drying process by Convection Oven of OA leaves

35

4.1.3.1 Determination of general equation 37 4.2 Continuous Microwave-vacuum Drying (MVD) of OA

Leaves 38

4.2.1 Drying Kinetics of OA Leaves from Continuous MVD

38

4.2.2 Optimisation of Continuous MVD of OA Leaves Using Response Surface Methodology (RSM)

42

4.2.3 Rosmarinic acid content of OA Leaves from Continuous MVD

43

4.2.4 Curve Fitting of Drying process by Continuous MVD of OA Leaves

45

4.2.4.1 Determination of general equation 48 4.3 Intermittent MVD of OA leaves 48 4.3.1 Drying Kinetics of OA Leaves from intermittent

MVD 48

4.3.2 Phytochemical content of OA Leaves from Intermittent MVD

50

4.3.3 Curve Fitting of drying process by Intermittent MVD of OA leaves

51

4.4 Convection oven drying of Eurycoma longifolia (EL) Roots 54 4.4.1 Drying Kinetic of EL roots from convection oven

drying 54

4.4.2 EUR content of dried EL roots from convection oven drying

55

4.4.3 Curve Fitting of drying process by convection oven of EL roots

56

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4.4.3.1 Determination of general equation 58 4.5 Continuous Microwave-vacuum Drying (MVD) of EL roots 59 4.5.1 Drying Kinetics of EL roots from continuous MVD 59 4.5.2 Optimisation of Continuous MVD of EL Roots Using

Response Surface Methodology (RSM) 63

4.5.3 EUR content of dried EL roots from continuous MVD

64

4.5.4 Curve Fitting of Drying process by Continuous MVD of EL roots

65

4.5.4.1 Determination of general equation 68 4.6 Intermittent MVD of EL roots 69 4.6.1 Drying Kinetics of EL roots from intermittent MVD 69 4.6.2 EUR content of dried EL roots from Intermittent

MVD 71

4.6.3 Curve Fitting of drying process by Intermittent MVD of EL roots

72

5 CONCLUSION 74 5.1 Conclusion 74 5.2 Recommendations for Future Research 74 REFERENCES 76APPENDICES 82BIODATA OF STUDENT 120LIST OF PUBLICATIONS 121

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LIST OF TABLES Table Page 2.1 Previous researches using convective hot-air drying method for

different herbal leaves 13

2.2 Previous researches using conventional drying method for

different types of agricultural products 14

2.3 Application of microwave-vacuum (continuous and intermittent

modes) and parameters selected in drying of fruits, vegetables and aromatic plant materials

17

3.1 Central-composite experimental design of the independent

variables 26

3.2 Total drying time and PR applied in the intermittent MVD 27 3.3 The mobile phase change in HPLC analysis 29 3.4 The mobile phase change in UPLC analysis 29 3.5 Mathematical models applied to the drying curves 31 4.1 The values of R2, RMSE and drying constants for thin-layer

drying models from convection oven drying of OA leaves 36

4.2 Regression estimate of a, k, n and b in Midili et al. model for

convection oven 37

4.3 Optimum condition for MVD of OA leaves 42 4.4 The values of R2, RMSE and drying constants for thin-layer

drying models from MVD of OA leaves

45

4.5 Regression estimate of a k, n and b in Midili et al. model for MVD 48 4.6 The values of R2, RMSE and drying constants for thin-layer

drying models from intermittent MVD of OA leaves 52

4.7 The values of R2, RMSE and drying constants for thin-layer

drying models from convection oven of EL roots 58

4.8 Regression estimate of a k, n and b in Midili et al. model for

convection oven of EL roots 59

4.9 Optimum condition for MVD of EL roots 63

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4.10 The values of R2, RMSE and drying constants for thin-layer drying models from MVD of EL roots

66

4.11 Regression estimate of a k, n and b in Midili et al. model for MVD

of EL roots 69

4.12 Drying time for intermittent and continuous MVD of EL roots at

150 W and 50.0 kPa vacuum pressure 70

4.13 The values of R2, RMSE and drying constants for thin-layer

drying models from intermittent MVD of EL roots 73

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LIST OF FIGURES Figure Page 2.1 Orthosiphon aristatus plants with white flower 5 2.2 Chemical structure of rosmarinic acid 6 2.3 Eurycoma longifolia plants 8 2.4 Eurycoma longifolia roots used for herbal products 9 2.5 Chemical structure of eurycomanone 10 2.6 Typical drying curves using moisture content vs. time and drying

rate curve using drying rate vs. moisture content 12

3.1 Overview of the methodology of this research project 22 3.2 Schematic diagram of MVD unit at Agricultural Process

Engineering Lab in Process and Food Engineering Department, UPM

23

3.3 Orthosiphon aristatus leaves on petri dishes during drying 24 3.4 Eurycoma longifolia roots on petri dishes during drying Division,

FRIM 24

3.5 Schematic diagram of convection oven at the lab of Natural

Products in Process and Food Engineering Department, UPM 25

4.1 Drying curves of OA leaves dried at 45, 50 and 55°C using

convection oven 33

4.2 Drying rate curves of OA leaves dried at 45, 50 and 55°C using

convection oven 34

4.3 Concentration of RA in fresh and dried leaves subjected to

different drying temperatures 35

4.4 Comparison between the experimental data and the predicted

model for drying temperatures 45, 50 and 55°C 37

4.5 Drying curves of OA leaves dried at selected vacuum pressure

levels 39

4.6 Drying curves of OA leaves dried at 225 W 40

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4.7 Drying rate curves of OA leaves dried at selected vacuum pressure levels

41

4.8 Response surface graph showing the interaction of microwave

power and vacuum pressure on RA concentration 43

4.9 Concentration of RA from leaves dried using continuous-MVD

and convection oven 44

4.10 Comparison on the experimental data at 32.5 kPa vacuum

pressure with the predicted model 47

4.11 Comparison on the experimental data at 15.0 kPa vacuum

pressure with the predicted model 47

4.12 Drying curves of OA leaves dried using intermittent MVD at 300

W and 50.0 kPa vacuum pressure 49

4.13 Drying rate curves of OA leaves dried using intermittent MVD at

300 W and 50.0 kPa vacuum pressure 50

4.14 Concentration of RA from intermittent MVD at 300 W and 50.0

kPa vacuum pressure 51

4.15 Comparison between the experimental data with the predicted

model 53

4.16 Drying curves of EL roots dried at 40, 50, 60 and 70°C using

convection oven 54

4.17 Drying rate curves of EL roots dried at 40, 50, 60 and 70°C using

convection oven 55

4.18 EUR concentration in EL roots subjected to convection oven

temperature of 40, 50, 60 and 70°C 56

4.19 Comparison between the experimental data at 40, 50, 60 and

70°C with predicted model 57

4.20 Drying curves of EL roots dried at selected microwave power 60 4.21 Drying rate curves of EL roots dried at selected microwave power 62 4.22 Response surface graph showing the interaction of microwave

power and vacuum pressure on EUR concentration 63

4.23 Concentration of EUR from continuous-MVD dried roots at

different drying conditions 64

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4.24 Temperature profiles during continuous-MVD at 32.5 kPa vacuum pressure

65

4.25 Comparison on the experimental data with predicted (Midili et

al.) model for MVD of EL roots at selected vacuum pressure levels

68

4.26 Drying curves of EL roots dried using intermittent MVD at 150

W and 50.0 kPa vacuum pressure 70

4.27 Drying rate curves of EL roots dried using intermittent MVD at

150 W and 50.0 kPa vacuum pressure 71

4.28 Concentration of EUR from intermittent-MVD at150 W and 50.0

kPa vacuum pressure 72

4.29 Comparison on the experimental data with predicted (Midili et

al.) model for intermittent MVD of EL roots 72

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LIST OF ABBREVIATIONS

MVD Microwave-vacuum drying

PR Pulsing ratio

OA Orthosiphon aristatus

EL Eurycoma longifolia

RA Rosmarinic acid

EUR Eurycomanone

RSM Response Surface Methodology

bo Regression coefficient of intercept term

b1 Linear regression coefficient

b2 Linear regression coefficient

b11 Squared regression coefficient

b22 Squared regression coefficient

b12 Interaction regression coefficient

Y Response of RSM

T Absolute temperature

HPLC High Performance Liquid Chromatography

UPLC Ultra Performance Liquid Chromatography

RMSE Root mean square error

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CHAPTER 1

INTRODUCTION

1.1 Herbal Industry in Malaysia The prospect of herbal and spices industry in Malaysia is very promising and anticipated to produce new source of wealth for the nation. Issues that need to be addressed by the industry includes technology application not optimum, insufficient supply of raw materials, inconsistent quality of raw materials, limited cultivation area, lack of focus on high-value herbal products and lack of investments from large companies (Mohd Hafizudin, 2015). Thus, the industry must be revived as Malaysia has been blessed with plentiful natural resources and massive number of species with medicinal potential. In Malaysia, there are market growth per annum of 10 to 15% for pharmaceutical and herbal remedies, and 20% for health and functional food (Zurinawati, 2004). Resulting from this growing market, tremendous effort has been carried out in order to discover highly valuable plants and turn it into finished products. 1.2 Herbal Postharvest Processing Herbal postharvest processing refers to primary processing following harvesting process including cooling, cleaning, sorting, drying, grinding and packaging. It is important to produce herbal products with good quality and conforms to market regulations and guidelines in order to penetrate into the global market. The goals in postharvest processing are:

i) to improve quality and value of herbs ii) reduce postharvest losses iii) optimize herbal processing to maintain shelf life

Initial postharvest drying conditions are critical to avoid moisture loss and slow down undesirable chemical changes. It is an oldest preservation technique to maintain shelf-life with regards to physical appearance, taste, flavour and texture. Drying refers to the thermal processes that aimed to reduce moisture content of fruits and vegetables, and it is one of the time and energy consuming processes in the food industry (Puligundla et al., 2013). Combination methods such as sensorial, biochemical, mechanical and colorimetric measurements are involved in drying, but focused technology is on the biochemical marker and fingerprint methods as indices for quality control (Li et al., 2008).

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1.3 Problem statements Orthosiphon aristatus (OA) and Eurycoma longifolia (EL) are valuable medicinal plants that have significant potential in the production of healthcare products and food supplements in Malaysia. The plants were listed under the national herbal species under the Agriculture National Key Economic Area (NKEA) initiative for the herbal sub-sector. In herbal processing, dehydration is the most crucial part because this step is part of the product development process for powdering, tea making, extraction, capsuling and tabletting. Fresh harvested plants and semi-processed plants were used as starting material. In Malaysia, most of the commercial products derived from OA are in a form of herbal tea processed from the dried leaves. Tea processing involves particle size reduction of the dried leaves, packaging, sterilization and quality control. On the other hand, commercial products derived from EL are in a form of capsules and 3-in-1 beverages. Manufacturing these products involve dried materials as input that are microbial-free to ensure the products are safe to be consumed. Convection oven drying is widely used in herbal industry for herbal drying. The drawback in this drying method are time-consuming (Arslan & Musa, 2010), quality degradation due to heat exposure (Jaloszyński et al., 2008; Lin et al., 2010; Giri & Prasad, 2007) and unavailability of standard drying parameters to maintain product quality. Applying microwave energy to food material seems to be applicable approach for coping with disadvantages in conventional drying. When microwave energy applies to food materials, heat is generated within the product. Temperature of the product increase rapidly resulting in faster water removal than conventional drying. This contributes to saving time and energy. However, microwave drying can caused product damage caused by excessive heating which may be due to poorly controlled heat and mass transfer (Ramaswamy & Marcotte, 2006). Two strategies were applied for drying food materials using microwave technology. The strategies using vacuum in the dryer to lower drying temperature and application of microwave energy in a pulsed manner to maximize drying efficiency since continuous heating does not accelerate the rate of water removal when critical moisture content is reached. Microwave drying assisted with vacuum had reported previously to be used successfully for the dehydration of various fruits, vegetables and aromatic herbs including rosemary (Calín-Sánchez et al., 2011), edamame (Qing-guo et al., 2006), grapes (Clary et al., 2007), potato (Bondaruk et al., 2007), tomato (Abano et al., 2013), green peas (Chauhan & Srivastava, 2009), carrots (Cui et al., 2005), mushrooms (Giri & Suresh, 2007), apples (Han et al., 2010) and berries (Mitra & Meda, 2009). However, its application in medicinal herbs is still scarce. The dryer also not exist commercially, mostly are laboratory scale and research done tailored to the product. The present study was to access the beneficial of this drying technology and

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investigate its performance to OA leaves and EL roots in term of their drying kinetics and phytochemicals quality.

1.4 Objectives

The objectives of the study were:

To determine the effects of microwave-vacuum drying techniques on dryingkinetics and phytochemicals content of OA leaves and EL roots.

To determine the optimum drying condition based on phytochemicals contentof OA leaves and EL roots.

1.5 Scope of Research

The scope of this research work covered drying process for the leaves of Orthosiphon aristatus (OA) and roots of Eurycoma longifolia (EL) using microwave-vacuum drying (MVD) technique. The influence of two variables from MVD namely microwave powers ranging from 150 to 300 W and vacuum pressures ranging from 15 to 50 kPa were studied based on drying kinetics and selected phytochemicals quality. The design of the experiments and process optimization was done using Response Surface Methodology (RSM) from Design-Expert software, a tool for process optimization. Modes of drying for MVD were at continuous and intermittent. At intermittent mode, pulsing ratios of 2, 3 and 4 were applied.

The selected phytochemicals for OA leaves and EL roots were Rosmarinic acid (RA) and Eurycomanone (EUR), respectively. The quality of the dried leaves and roots based on these phytochemicals at different drying condition was quantified using liquid chromatography. Three thin-layer drying models namely Page, Midili and Logarithmic were chosen to fit the experimental data in order to select the best model to represent MVD process for both type of herbs.

Convection oven drying was selected as control drying method. Drying temperatures applied for OA leaves were 45, 50 and 55°C, while for EL roots were 40, 50, 60 and 70°C. Optimum drying temperatures based on phytochemicals content were selected and used in the study.

1.6 Structure of the Thesis

The thesis comprises five chapters. Firstly, Chapter 1 introduces the research problem as well as outlines towards the thesis conclusions. Chapter 2 provides literature review in which the theoretical, knowledge sharing as well as the hypotheses arising from knowledge developed during the literature review. Chapter 3 describes and explains the method used and data collection in this study. Chapter 4 summarizes the results applying the method in this study. Finally, Chapter 5 contains the conclusions about

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the hypotheses and research issues based on the results of Chapter 4 and their implications for practice as well as future research.

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BIODATA OF STUDENT  

Hada Masayu Ismail @ Dahlan is currently working as Research Officer in Forest Research Institute Malaysia (FRIM), Kepong. She holds a Bachelor’s Degree in Process and Food Engineering from Universiti Putra Malaysia (UPM). Her research interests include drying technology and postharvest processing of herbal raw materials. At FRIM, she was given the responsibility to take care of FRIM’s Maran Research Station, Pahang, and is directly involved in research work related to post harvest technology of herb. She has 11 years of working experience at FRIM.

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LIST OF PUBLICATIONS

Journal Submitted

Hada Masayu Ismail, Mohd. Nordin Ibrahim, Rabitah Zakaria, Pin Kar Yong & Mohd. Radzi Ahmad. (2016) . Effects of convection oven drying on drying kinetics and quality of Eurycoma longifolia Jack. Submitted to Bioresource Technology Journal.

Journal to be Submitted

Mohd. Nordin Ibrahim, Hada Masayu Ismail, Pin Kar Yong & Rabitah Zakaria, Mohd. Radzi Ahmad. (2016) . Effects of microwave-vacuum drying on drying kinetics and quality of Eurycoma longifolia Jack. Food Research.

Proceedings Conference

2016

Hada Masayu Ismail, M. Nordin Ibrahim, Rabitah Zakaria, M. Farhan Abd. Razak, Pin Kar Yong. (2015). Effects of microwave-vacuum drying technique on drying kinetics and quality of Orthosiphon aristatus leaves. Proceedings of the 14th Seminar on Medicinal and Aromatic Plants 2016. (Eds. B. J. Chee, M. Mastura, K. Getha, M. G. H. Khoo, J. Mailina, M. A. Adiana, M. S. Roshan Jahn, Selangor, Malaysia (11-12 October 2016) ISBN 978-967-0622-66-8

2015

Hada Masayu Ismail, M. Nordin Ibrahim, Pin Kar Yong, Rabitah Zakaria, M. Radzi Ahmad. (2016). Effects of temperature on drying of E.longifolia Jack Roots: Drying time and product quality. Proceedings of the 8th Asia-Pacific Drying Conference ADC 2015. (Eds. Chung Lim Law, Ching Lik Hii, Sze Pheng Ong, Choon Lai Chiang, Pau Loke Show and Ianatul Khoiroh), Kuala Lumpur, Malaysia (10-12 August 2015) ISBN 978-967-11279-2-6

Hada Masayu Ismail, M. Nordin Ibrahim, Pin Kar Yong, Rabitah Zakaria, Sofia Azman, Mohd. Shahidan M. Arshad. (2015). Drying of Eurycoma longifolia jack (tongkat ali) by microwave-vacuum drying. Proceedings of the Conference of Forestry and Forest Products Research (CFFPR), Kuala Lumpur. 21-23 December 2015.

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2013 Hada Masayu, I.D., M Nordin, I., Pin, K.Y., Zamree, M.S. , Mohd. Shahidan , M.A.,

Noor Rasyila, M.N., & Khairul Kamilah, A.K. (2013). Drying kinetics of microwave-vacuum and convective oven drying of misai kucing (Orthosiphon aristatus). Proceedings of the Conference of Forestry and Forest Products Research 2013 "Forestry R, D & C: Meeting National and Global Needs", 11–12 November 2013, Kuala Lumpur.

Conference Abstract 2014 Hada Masayu Ismail, M. Nordin Ibrahim, Pin Kar Yong, Rabitah Zakaria, Sofia

Azman, Mohd. Shahidan M. Arshad. (2014). Drying kinetics of microwave-vacuum drying of Eurycoma longifolia jack (tongkat ali). by microwave-vacuum drying. Paper presented at the 2nd International Conference on Agricultural and Food Engineering CAFEi2014, Kuala Lumpur. 1-3 December 2014.

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STATUS CONFIRMATION FOR THESIS / PROJECT REPORT AND COPYRIGHT

ACADEMIC SESSION : SECOND SEMESTER 2016/2017

TITLE OF THESIS / PROJECT REPORT :

EFFECTS OF MICROWAVE-VACUUM DRYING ON DRYING KINETICS AND QUALITY OF Orthosiphon aristatus (BLUME) MIQ. LEAVES AND Eurycoma longifolia JACK ROOTS

NAME OF STUDENT: HADA MASAYU BINTI ISMAIL @ DAHLAN

I acknowledge that the copyright and other intellectual property in the thesis/project report belonged to Universiti Putra Malaysia and I agree to allow this thesis/project report to be placed at the library under the following terms:

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