Detection and quantification of non-milk fat in mixtures of milk and non-milk fats

Abstract

SUMMARYThe triglyceride compositions of 76 Australian milk fats obtained from 3 factories during a whole year were determined by gas-liquid chromatography. It was shown that all the data fitted the equationwith a S.D. of of 0·7088 where C40, C42 and C44 are the weight percentages of triglycerides with carbon numbers 40, 42 and 44. The triglyceride compositions of 10 samples of milk fat from countries other than Australia were also shown to fit the equation. If the equation is assumed to define pure milk fat, it is shown that as little as 5% of any non-milk fats can be detected with > 99% confidence. The amount of non-milk fat in mixtures of milk and non-milk fats can be quantified to better than ±2% with > 95% confidence. Also, the identity of the non-milk fat can usually be deduced by calculation of its triglyceride composition. Analyses of known mixtures and of chocolate and a table spread comprising butter and vegetable oil showed an agreement between observed and expected results well within the predicted confidence limits.