DETECTION OF FOREIGN FAT IN MILK-FAT .1. QUALITATIVE DETECTION BY TRIACYLGLYCEROL FORMULAS

A sensitive method for the detection of vegetable fats and animal depot fat in milk fats based on gas chromatographic triacylglycerol analysis is described. The study included 755 different milk fat samples and 20 foreign fats for which the triacylglycerol composition was determined. On the one hand, all analyzed milk fats were mixed in a computer simulation with different foreign fat amounts and then a mixture recorded as modified milk fat if only one triacylglycerol was found to be outside the ranges of variation measured for pure milk fats. On the other hand, triacylglycerol formulae were established using statistical procedures allowing detection of foreign fats with substantially improved sensitivity. For the foreign fats, soybean oil, sunflower oil, olive oil, coconut oil, palm oil, palm kernel oil, lard and beef tallow, limits of detection of 1.3%, 1.2%, 1.7%, 2.5%, 2.7%, 2.9%, 1.9%, and 4.1%, respectively, were established with 95% confidence and only slightly higher values with 99% confidence. Experimental confirmation of the results was obtained using 24 mixtures from milk fats with low amounts of foreign fat admixtures (2%). The very sensitive detection method is only suited to be used for reliable qualitative detection when only a single foreign fat type has been added to milk fat.