Enzymatic Degradation of Egg Yolk Cholesterol

The capacity of four cholesterol oxidases from Nocardia erythropolis (Ne), Streptomyces species (Ss), Brevibacterium species (Bs) and Pseudomonas fluorescens (Pf) to degrade cholesterol in egg yolk at 4, 25 and 37°C has been determined. The effects of enzyme/substrate concentration and incubation temperature on the enzymatic activity of these cholesterol oxidases have also been investigated. The cholesterol degrading capacity of these enzymes follows the sequence Pf>Ne>Ss>Bs. Up to 93.4% cholesterol was degraded by cholesterol oxidases from P. fluorescens and Streptomyces species after 72 h of incubation at 37°C. At 4°C, P. fluorescens cholesterol oxidase could degrade up to 64.9% cholesterol after 48 h.