Quantitation of milk fat in mixtures of butter oil and partially hydrogenated vegetable fats

The analysis of butyric acid (C4) allows to quantify the milkfat content in a mixed fat, as C4 exclusively occurs in milkfat. Such a method is of inte rest e.g. for the control of the declared composition of mixed spreadable f ats. The methodology for precising milkfat quantitation could be determined by using a recently improved method for analyzing model mixtures made from partially hydrogenated vegetable fats, extracted from margarine and cookin g fat, with contents of 1, 2, 3, 4, 5, 8, 10, 15, 20, 30, 40, 50, 60, 70, 8 0 and 90 % butter oil. The fact of including the C4 content of the underlyi ng pure milkfat (component sample) led to absolute deviations between calcu lated and actual milkfat content of 0.46 % on average in the range of 10-80 % milkfat pre-set for mixed spreadable fats in the EU. The maximum deviati on was about 1 %. For milkfat contents of less than or equal to 10 % the ab solute error was distinctly lower. However, due to the natural variation of the butyric acid content in milkfats, the application of a mean C4 content instead of the actual content of C4 in the component sample may cause rela tive deviations of over 10 %.