Comparison of Four Different Methods for Egg Cholesterol Determination

Abstract

Eggs were collected from 48-wk-old, Single Comb White Leghorn hens fed a wheat and soybean meal-based laying hen ration. Yolks were separated, and five yolk samples were prepared by pooling three yolks per sample. Yolk samples were saponified and extracted with hexane. The hexane extracts were assayed for cholesterol by four different methods: colorimetric, enzymatic, gas chromatographic (GC), and HPLC. The traditional colorimetric method was found to overestimate the yolk cholesterol concentration when compared with the enzymatic, GC, or HPLC methods. No free fatty acids or triglycerides was detected in hexane extracts; therefore, the overestimation by the colorimetric method could not be attributed to contamination by free fatty acids or triglycerides. Cholesterol contents determined by enzymatic, GC, and HPLC methods were not significantly different from each other. All three methods had excellent precision.