Preparation of prepared solution and conditions for the quantitative analysis of steryl esters in milk fat by gas-liquid chromatography (GLC) were investigated, and components of steryl esters in various dairy products were analysed. Results obtained may be summarized as follows:
1. Clean-up of the preparated solution by a silicic acid column technique was superior to that by the thin-layer chromatographic separation.
2. Steryl esters in commercial milk fat were found to consist of cholesteryl esters of C-10, C-12, C-14, C-16, C-18 and C-20, in which the most predominant component was the C-18 ester. However, the amount of C-18 ester in milk fat was rather inconsistent showing a marked seasonal variation in the level.
3. GLC analysis of steryl esters was carried out using cholesteryl cinnamate as an internal standard. Ratios of cholesteryl esters of C-18 to C-16 in milk fat were much higher than those values obtained with so-called synthetic (commerical milk fat) or imitation milk fat. The ratio of cholestleryl esters of C-18 to C-16 may be applicable for the identification of so-called synthetic milk fat in various dairy products, especially, may fit for detecting adulterated or unnatural milk fat.
4. Judging from the retention time of GLC, the fatty acid components and the total amount of cholesterol in a so-called synthetic milk fat were almost the same as those of the natural milk fat, whereas the triglyceride components in both types of milk fat were distinguished each other according to GLC being equipped with a column of good separating ability (theoretical plate number of the column was more than 800 when calculated for tristearin).
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