CONTENTS Page
Abstract xiii
Publications & Communications xv
List of Abbreviations xvi
List of Figures and Tables xviii CHAPTER 1 Literature Review
Introduction 92
Preparation and Characterisation of COD 93
Specificity and Mode of Action of COD 94
Cofactors of Cholesterol Oxidase 96
Cholesterol Oxidation Byproducts 96
COD Activity and Cholesterol Assay 97Potential Application for Cholesterol Degradation 98
Results and Discussion 99
Effect of Time and Temperature 99
Effect of Concentration 105Cholesterol Degradation Products 107 CHAPTER 5
Microbial Degradation of Egg and Milk Cholesterol
Cholesterol Degradation in Milk 120
Effect of Culture Growth Medium on the Cholesterol Degrading Activity of Cells in Milk and Egg Yolk 121
A Comparison of Milk and Egg Yolk CholesterolDegradation 124
Products of Cholesterol Degradation in Egg Yolk
COMMUNICATIONSThe following communications have been presented to learned societies:
Christodoulou S., T. V. Hung, M.A. Trewhella and R. Black (1993)
Enzymatic degradation of egg cholesterol 26th Convention ProceedingsA I F S T 2nd-6th May, Adelaide PP.4.
Christodoulou S., T. V. Hung, M. A. Trewhella and R. Black (1993)Cholesterol content of some western foods and oriental analogues X V International Congress of Nutrition 26 September-1st October, Adelaide P31.
Christodoulou S., T. V.Hung, M. A. Trewhella and R. Black (1994)
Degradation of milk and egg cholesterol by enzymes and microorganisms 24thInternational Dairy Congress 18th-22nd September, Melbourne.
E g g Nutritional ValueEggs are among the most nutritious foods known, providing a unique, wellbalanced source of nutrients for persons of all ages. They contribute to the body's nutrient needs during rapid growth, and are an excellent food for young children and teenagers. Their high nutrient content, comparatively low caloric value and ease of digestibility make eggs valuable in many therapeutic diets for adults (Cook and Briggs, 1977).Although eggs contain about 74% water, they are a rich source of high qual proteins. Experimental nutritionists use egg proteins as a standard for measuring the quality of other food proteins (Cook and Briggs, 1977). Eggs are also an important source of iron, phospholipids, trace minerals, vitamin A, B (including B12), E and K. A s a source of vitamin D, eggs rank second only to fish-liver oils.Eggs are low in calcium, however, and contain very little, or no, vitamin C (Cook and Briggs, 1977).
Egg CompositionWhole egg is composed of approximately 64% white and 36% yolk (Pratt, 1975 The yolk contains all of the egg lipid; 195-270mg/egg (Feeley, 1972; Beyer and Jensen, 1989a; Holden et al, 1989,).Most of the cholesterol in egg yolk is found in the low density lipoprotei (Gornall and Kuksis, 1971). The composition of L D L in egg yolk comprises of protein (11-17%), phospholipid (22-28%) and neutral lipid (59-67%) (Holdsworth and Finean, 1972).Egg yolk LDL particles appear to be spheres of lipid surrounded by a layer glycoprotein, phospholipid and cholesterol with hydrophobic groups on ...
