Detection of non-milk fat in milk fat by gas chromatography and linear discriminant analysis

Abstract 

Gas chromatography was utilized to determine triacylglycerol profiles in milk and non-milk fat. The values of triacylglycerol were subjected to linear discriminant analysis to detect and quantify non-milk fat in milk fat. Two groups of milk fat were analyzed: A) raw milk fat from the central region of Mexico (n=216) and B) ultrapasteurized milk fat from 3 industries (n=36), as well as pork lard (n=2), bovine tallow (n=2), fish oil (n=2), peanut (n=2), corn (n=2), olive (n=2), and soy (n=2). The samples of raw milk fat were adulterated with non-milk fats in proportions of 0, 5, 10, 15, and 20% to form 5 groups. The first function obtained from the linear discriminant analysis allowed the correct classification of 94.4% of the samples with levels <10% of adulteration. The triacylglycerol values of the ultrapasteurized milk fats were evaluated with the discriminant function, demonstrating that one industry added non-milk fat to its product in 80% of the samples analyzed.

Key words: gas chromatography, linear discriminant analysis, non-milk fat, milk fat