Dedicated to my mother, father and sister MUSTARD AND RAPESEED OILS: AUTHENTICITY, SEED ROASTING AND OXIDATIVE STABILITY Thesis submitted in fulfillment of the requirements for the degree of Doctor (PhD) in Applied Biological Sciences: Chemistry Promotor: Prof. Dr. ir. Bruno De Meulenaer NutriFOODchem Unit, Department of Food Safety and Food Quality, Faculty of Bioscience Engineering, Ghent University Examination committee: Prof. Dr. ir. Christophe Blecker Unité de Science des Aliments et Formulation, Gembloux Agro-Bio Tech, Université de Liège Prof. Dr. ir. Stefaan De Smet (Chairman) Department of Animal Production, Ghent University Prof. Dr. ir. Matthias D’hooghe SynBioC Research Group, Department of Sustainable Organic Chemistry and Technology, Ghent University Dr. Bertrand Matthäus Max Rubner-Institut (MRI), Bundesforschungsinstitut für Ernährung und Lebensmittel, Institut für Sicherheit und Qualität bei Getreide Prof. Dr. Ashok Patel Laboratory of Food Technology and Engineering, Department of Food Safety and Food Quality, Ghent University Prof. Dr. ir. Paul Van der Meeren Research Group Particle and Interfacial Technology, Department of Applied Analytical and Physical Chemistry, Ghent University Dean: Prof. Dr. ir. Guido Van Huylenbroeck Rector: Prof. Dr. Anne De Paepe Dutch translation of the title: Mosterd en raapzaad olie: authenticiteit, zaad roosteren en oxidatieve stabiliteit Cover photo: http://deliciousontap.co.uk/ Printed by: University Press BVBA- [email protected] To refer to this thesis: Shrestha, K. (2014). Mustard and rapeseed oils: authenticity, seed roasting and oxidative stability. PhD dissertation, Faculty of Bioscience Engineering, Ghent University, Ghent. ISBN: 978-90-5989-682-6 The author and promotor give the authorization to consult and copy parts of this work for personal use only. Every other use is subject to the copyright laws. Permission to reproduce any material contained in this work should be obtained from the author. MSc Kshitij Shrestha was financially supported by the Special Research Fund (BOF), Ghent University. The research was performed in the laboratory of the Research Group Food Chemistry and Human Nutrition, Department of Food Safety and Food Quality, Faculty of Bioscience Engineering, Ghent University. Acknowledgements My journey to Belgium began when I got a VLIR scholarship in 2007 to pursue a Master‟s degree in Food Technology at Ghent University. During that time, I got an opportunity to work with my current promotor. It was his advice and guidance that led me to start my PhD research with the support from Special Research Fund (BOF). I am extremely grateful to BOF (Ghent University) for funding my PhD research. After coming to Belgium, I came to learn a new word “promotor”, which is not common in my country. At first, I was wondering what actually does this terminology mean? After working for so long time with my promotor, I slowly came to understand the meaning behind it. I realized that promotor is not just a supervisor to monitor your work and a guide to show you the path. But a promotor is the one who promotes your work, understands your strength and weakness, motivates you when you are frustrated, and pulls you out when you are stuck with a problem. I would like to express my sincere gratitude to my promotor Prof. Dr. ir. Bruno De Meulenaer for all the support he has given to me, both personally and professionally. Thank you for believing me and motivating me even during my difficult and challenging days. I am also thankful to Prof. Dr. ir. Liesbeth Jacxsens and Prof. Dr. ir. Christian V. Stevens for the fruitful discussions, guidance and support during my research. I would also like to thank all the members of the examination committee for the time, critical evaluation and insightful questions. Frederic and Barbara, you were supervisors during my master thesis and you also helped me during the starting days of my PhD. Thank you so much for all your support. Tania, Nathalie, Sofie, Evelien, Bryan, Laurens, Laurent, Angelique, Johana, Charlotte, Anne, Kimberley, Nanou, Dieter and Karin, I would like to express my gratitude and thanks for all the help you provided me during the research. Remembering all those past days, I feel very lucky as I was always accompanied by so many good friends around me all the time. Edward, and Antonios, we had a great group. I will always remember those crazy ideas and great memories we shared. Imen and Stas, we shared the same office room during the start of our work and both of you remained very good friends till the end. Monica, Loan, Bea, Agnieszka, Amr, Merry, Gustavo, Kathy, I will always remember the great time I spent with all of you. Theeba and Mai, you remained very good friends from the start of our Master course until now. To all of you and other colleagues, thank you for the great company, smiles, friendship, help, support and fun you gave to me. I would also like to thank all the Master thesis students, who helped me during my studies. Srijana and Gokarna, thanks for your great company and help. Sashi dai, Durga dai, Ashish and Sambridhi, thanks for your help during my stay. I would also like to express my sincere gratitude to the Director General of DFTQC Jiwan Prava Lama for her continuous support and help during my study. Luna, Krishna, Jitendra and Achyut, thanks for the help during the collection of samples. Special thanks go to Roji for her continuous support, help and patience during the entire period of my work. I am grateful to my sister, Roshana Shrestha, who has been the most inspiring and supporting person during my entire life. I also thank my brother-in-law for his help and express love to my daughter-in-law Ayusha. Finally, I would like to express my sincere gratitude to my parents for their continuous support, guidance, inspiration, blessings and love, without which, I could neither have succeeded in this research work nor in my life. I am indebted to you for my entire life. I would like to dedicate my PhD thesis to you. Thank you all. Kshitij Shrestha 12th February, 2014 Ghent TABLE OF CONTENTS LIST OF ABBREVIATIONS ..................................................................................................... v INTRODUCTION AND OBJECTIVES ................................................................................. vii SUMMARY .................................................................................................................................. xi SAMENVATTING ..................................................................................................................... xv 1 LITERATURE REVIEW ON MUSTARD AND RAPESEED OILS: ADULTERATION, LIPID OXIDATION, OXIDATIVE STABILITY AND SEED ROASTING ........................................................................................................................... 1 1.1 INTRODUCTION TO MUSTARD AND RAPESEED .............................................. 3 1.2 ADULTERATION/AUTHENTICITY.......................................................................... 6 1.2.1 Problem of oil blending/adulteration in the Nepalese market .............................. 6 1.2.2 Chemometric approaches used previously to authenticate oils and estimate oil adulteration .............................................................................................................. 7 1.3 LIPID OXIDATION AND OXIDATIVE STABILITY .............................................. 8 1.3.1 Introduction ............................................................................................................. 8 1.3.2 Factors affecting lipid oxidation .......................................................................... 10 1.4 EFFECT OF SEED ROASTING ON OIL OXIDATIVE STABILITY ................... 16 2 MONTE CARLO SIMULATION BASED PREDICTION OF BLENDED OIL COMPOSITION CONTAINING MUSTARD, RAPESEED AND SOBYEAN OILS ................................................................................................................................................ 19 2.1 INTRODUCTION ........................................................................................................ 22 2.2 MATERIALS AND METHODS ................................................................................. 22 2.2.1 Samples and chemicals ......................................................................................... 22 2.2.2 Analytical methods................................................................................................ 23 2.2.3 Monte Carlo simulation and statistical analysis .................................................. 24 2.3 RESULTS AND DISCUSSION .................................................................................. 26 i 2.3.1 Development of a Monte Carlo simulation based method for the prediction of blend composition ................................................................................................. 26 2.3.2 Evaluation of the developed Monte Carlo simulation method in the real mixture of soybean oil and HEARM oil (step 7 and 8 of Figure 2-1) ............................. 32 2.3.3 Evaluation of the developed Monte Carlo method by simulation study and calculation of limit of detection (LOD) (step 9 of Figure 2-1) .......................... 35 2.3.4 Application of the Monte Carlo simulation method in the Nepalese samples (step 10 of Figure 2-1) .......................................................................................... 37 2.4 CONCLUSIONS ..........................................................................................................