TABLE OF CONTENTS 



ACKNOWLEDGEMENTS ii 



LIST OF TABLES vii 



LIST OF FIGURES viii 



ABSTRACT xii 



INTRODUCTION 1 



LITERATURE REVIEW ... 4 



' Polyphenol Oxidase 4 



\ Enzymatic Browning (Melanosis) 6 



Inhibition/Prevention of Melanosis 9 



Kojic Acid 12 



I Supercritical Fluid (SCF) Treatment 12 



'■ CHARACTERIZATION AND COMPARISON OF CRUSTACEAN AND PLANT POLYPHENOL 



fr OXIDASES: KINETICS AND SOME PROPERTIES 16 



it 



* 



I Introduction 16 



f Materials and Methods 17 



I Extraction and Purification of Lobster Polyphenol Oxidase 



(PPO) 18 



Extraction and Purification of Potato PPO 19 



Extraction and Purification of Apple PPO 20 



Extraction and Purification of White Shrimp and Grass Prawn 



PPO 21 



Protein Quantitation and Enzyme Purity Determination 23 



PPO Activity Determination 23 



pH Optima and Stability of Lobster PPO 24 



Activation Energy and Thermostability of Lobster PPO 24 



Molecular Weight Determination of Lobster PPO 25 



Enzyme Kinetics Study 26 



Results and Discussion 26 



Effect of pH on Lobster PPO Activity 26 



Effect of pH on Lobster PPO Stability 31 



Effect of Temperature on Lobster PPO Activity and Stability . 31 



Activation Energy (E^) of Lobster PPO 39 



Molecular Weight and Isoform Determination of Lobster PPO . . 40 



Enzyme Kinetics of Lobster PPO 43 



i i i 



