Rapid Method for Isolation of Unesterified Sterols and Its Application to Detection of Milk Fat Adulteration with Vegetable Oils

This is the authors' abstract. We don't add key points for this paper.

Unesterified sterols were isolated from 900-rag samples of fat by using a column of digitonin impregnated on Celite 545, Schwartz et al. (4), then eluting the sterols with dimethylsulfoxide.The sterols were extracted from the dhnethylsulfoxide with hexane-benzene mixtures in a condition suitable for analysis by gas-liquid chromatography.The addition of 1% corn, cottonseed, soybean, or peanut oil could be easily detected by the presence of fi-sitosterol.Coconut and safflower oil adulteration were detected at the 2% level.Because of small amounts of fl-sitosterol present in commercial emulsifiers, ice cream fat adulterated with corn, cottonseed, soybean, or peanut oil would be detected at the 2 to 2.5% level, while coconut and safflower oil adulteration would be detected at the 4 to 5% level.The adulteration of milk fat with vegetable oils is a continuing problem in the dairy industry.Although many methods have been developed to detect adulteration, only a few are considered reliable enough to be used as a routine laboratol:¢ procedure.The ot~cial AOAC procedure developed by Keeney (3) measures the butyric acid concentration of the suspected sample.Since butyric acid is found only in milk fat, addition of other fats and oils results in abnormally low butyric acid values.In practice one begins to detect adulteration at levels of 10% or more.Because of the large price differential between milk fat and vegetable otis, it is economically attractive to adulterate milk fat at levels of 5 to 15%.With the advent of gas-liquid chromatography, and the subsequent sophistication of the technique so that sterols may