Quantitative analysis of sterols in dairy products: experiences and remarks

In this work different analytical problems connected to the determination of sterols in dairy products by the International Provisional Standard IDF 159 were investigated. Results showed that accuracy of determination of the cholesterol content of milk fat strictly depended on the evaluation of the correction factor for the internal standard, and this evaluation should be made at the same time as the sample analysis. Based on the evidence for the presence of vegetable sterols also in pure milk fat, a limit of detectability of 4-5% for vegetable fat was determined in milk fat. Moreover, if this determination was applied to other dairy products than butter, the additional fat extraction step required could produce a further source of variability. In the case of whey cheese, the best recovery was obtained by alkaline hydrolysis followed by extraction with diethyl and petroleum ether. (C) 2002 Elsevier Science Ltd. All rights reserved.