Enzymatic Degradation of Egg Yolk Cholesterol

Abstract

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 ...

Egg and Egg-Derived Foods: Effects on Human Health and Use as Functional Foods

“…This methodology has obtained very promising results, but despite its potential, it is not used a lot on the industrial level because of its high price. Other recent methodology described for this purpose includes the selective degradation of cholesterol in egg yolks using the enzyme cholesterol oxidase together with ultrasound [ 99 ] or using different species of microorganisms [ 100 , 101 , 102 , 103 ]. Alternatively, cholesterol can be removed from egg yolks using microbial degradation or by complexation with β-cyclodextrin, alone or inmobilized in chitosan beads [ 104 , 105 ], high metoxyl pectins [ 106 ], Streamline Phenyl ® resin [ 107 ] anionic chelating agent [ 108 ] or low-cholesterol liquid food oil [ 109 , 110 ], or by obtaining egg yolk granules [ 111 ].…”

The genus Rhodococcus

“…Muconic acids can be produced by a strain of R. rhodochrous . Cholesterol oxidases from Rhodococcus have been studied and could have applications in the food industry or in steroid drugs' production (Finnerty 1992;Christodoulou et al 1994;Kreit et al 1994). Efficient production of the amino acids L-leucine and L-phenylalanine using Rhodococcus enzymes has been reported (Hummel et al 1987;Bhalla et al 1992).…”

Physical Factors and Reuse Affect the Production of Cholesterol Oxidase in Reactors Containing Calcium Alginate-Immobilized Rhodococcus equi No. 23

“…It has been used for the determination of cholesterol in blood serum and in the production of the precursor for chemical synthesis of steroid hormones (Watanabe et al 1986;Lolekha et al 2004). Furthermore, various investigators have demonstrated the degradation of cholesterol and low density lipoprotein by CholOx and indicated that the use of CholOx may provide an economic and practical method for reducing the amount of dietary cholesterol (Aihara et al 1988;Christodoulou et al 1994;Wu et al 1995;Watanabe et al 1989a;Kim et al 2002), which is partially related to cardiovascular disease, and hence serves to improve human health (Kaunitz 1978).…”