Development of a Novel Tomato (Solanum Lycopersicum) Peeling Process Using Power Ultrasound Technology
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DEVELOPMENT OF A NOVEL TOMATO (SOLANUM LYCOPERSICUM) PEELING PROCESS USING POWER ULTRASOUND TECHNOLOGY By CHERYL ROSITA ROCK A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2012 1 © 2012 Cheryl Rock 2 To Luke Ryan Redon, my angel in heaven (January 16, 1989-January 26, 2011) 3 ACKNOWLEDGMENTS I would like to express sincere thanks and appreciation to my advisory committee: Drs. Wade Yang (major advisor), Renee Goodrich, Liwei Gu, and Pratap Pullammanappallil for their invaluable support, suggestions and guidance pertaining to my research and matriculation in the Ph.D. program of the Department of Food Science and Human Nutrition at the University of Florida. Second, I would like to acknowledge my family (the Rocks and Metzgers) and closest friends: Luke Redon (Deceased), Braulio Macias, Tara Faidhalla, Jyotsna Nooji, Fredreana Hester, Tim Buran and Samira Lorne, who have always been there to uplift and offer me words of encouragement. Moreover, I would also like to express my deepest gratitude to Dr. Gloria Cagampang and my labmates Senem Guner, Sandra Shriver, Akshay Anugu, Xingyu Zhao, Bhaskar Janve, Syed Abbas (Ali), Ying Guo (Kelsey), Yiqiao Li (Chelsey) and Samet Ozturk for their continuous encouragement, moral support and advice. Last, I would also like to acknowledge Dr. Susan Percival, Mrs. Bridget Stokes and Drs. Charles Sims and Asli Odabasi for their guidance and kindness pertaining to the use of their lab facilities and equipment. Also, I would like to thank the office staff of the Food Science and Human Nutrition Department: Ms. Marianne Mangone, Mrs. Rhonda Herring, Ms. Shelia Parker, Ms. Julie Barber, Ms. Carmen Graham and Ms. Mary-Ann Spitzer for taking care of me during the course of my academic matriculation. 4 TABLE OF CONTENTS page ACKNOWLEDGMENTS .................................................................................................. 4 LIST OF TABLES ............................................................................................................ 9 LIST OF FIGURES ........................................................................................................ 10 LIST OF ABBREVIATIONS ........................................................................................... 11 ABSTRACT ................................................................................................................... 13 CHAPTER 1 INTRODUCTION .................................................................................................... 15 Justification of Study ............................................................................................... 17 Objectives ............................................................................................................... 18 2 LITERATURE REVIEW .......................................................................................... 19 Tomatoes ................................................................................................................ 19 Significance of Tomatoes in the Diet ...................................................................... 20 Lycopene .......................................................................................................... 22 Isomerization .................................................................................................... 22 Physical Factors ............................................................................................... 22 Light ........................................................................................................... 22 Thermal Treatment .................................................................................... 23 Active Surface Processing (Peeling) .......................................................... 23 Chemical Factors ............................................................................................. 23 Metal oxidation ........................................................................................... 23 Acidic isomerization ................................................................................... 24 Tomato Peeling Process ......................................................................................... 24 Significance of the Tomato Skin Structure in Peeling ............................................. 25 Tomato Skin Structure ............................................................................................ 25 Epicarp ............................................................................................................. 25 Cutin .......................................................................................................... 25 Acyl lipids ................................................................................................... 26 Hemicellulose ............................................................................................. 26 Phenylpropanoids ...................................................................................... 26 Pectin ......................................................................................................... 26 Pericarp ............................................................................................................ 26 Peeling .................................................................................................................... 27 Knife Peeling .................................................................................................... 27 Abrasive Peeling .............................................................................................. 27 Flame Peeling .................................................................................................. 28 5 Conventional Tomato Peeling Methods .................................................................. 28 Hot Water and Steam Peeling .......................................................................... 29 Lye Peeling ....................................................................................................... 30 Freeze-thaw Peeling ........................................................................................ 33 Enzymatic Peeling ............................................................................................ 33 Novel Tomato Peeling Methods .............................................................................. 35 Infrared Peeling ................................................................................................ 35 Ohmic Heating .................................................................................................. 37 Ultrasound ........................................................................................................ 40 Low-frequency Ultrasound................................................................................ 41 High-frequency Ultrasound ............................................................................... 42 Mechanism of Ultrasound Generation .............................................................. 42 3 EFFECTS OF PU, LYE AND STEAM ON THE PEELING PERFORMANCE OF ROMA TOMATOES ................................................................................................ 50 Background ............................................................................................................. 50 Materials and Methods............................................................................................ 51 Sample Collection and Preparation .................................................................. 51 Tomato Peeling ................................................................................................ 52 Lye ............................................................................................................. 52 Steam ........................................................................................................ 52 Power Ultrasound (PU) .............................................................................. 52 Peeling Performance of Roma tomatoes .......................................................... 53 Ease of peeling .......................................................................................... 53 Peeling loss ................................................................................................ 53 Peeled-pericarp thickness .......................................................................... 53 Statistical Analysis .................................................................................................. 53 Results and Discussion........................................................................................... 54 Ease of Peeling ................................................................................................ 54 Peeling Loss ..................................................................................................... 56 Peeled-Pericarp Thickness ............................................................................... 58 4 EFFECTS OF PU, LYE AND STEAM PEELING ON THE PHYSIOCHEMICAL PROPERTIES OF ROMA TOMATOES .................................................................. 64 Background ............................................................................................................. 64 Materials and Methods............................................................................................ 65 Peeled-tomato