Enzymatic-fluorometric quantification of cholesterol in bovine milk

The present paper describes an enzymatic-fluorometric method for the determination of cholesterol in milk and other opaque matrices. The initial step of the method is to liberate chemically and physically bound cholesterol from the milk fat globule membrane by enzymatic action. The method is able to discriminate between esterified and free cholesterol in milk. The analysis is cost effective and is developed to work directly on whole, fresh milk thereby eliminating time consuming and tedious pre-treatment procedures of the sample. More than 1000 milk samples were analysed on the day of sampling. The total concentration of milk cholesterol ranged from 80 to 756μM (n=1068; mean 351μM). Milk cholesterol was significantly correlated to milk fat concentration as analysed by mid-infra red spectrometry (r=0.630; n=853) and by an enzymatic-fluorometric method (triacylglycerol) (r=0.611; n=842).