Action of successive heat treatments in bovine milk fatty acids

The action of successive pasteurization thermal treatments (75 ºC for 15 s) and commercial sterilization by indirect heat exchange (140 ºC for 6 s) was analyzed on the lipid profile of bovine milk. Raw milk samples were submitted to pasteurization and then were submitted to sterilization (ultra-high temperature, UHT). The fat of raw milk, pasteurized milk and commercially sterilized milk samples was extracted. After transesterification, the fatty acid methyl esters (FAMEs) were analyzed by gas chromatography with flame ionization detector (GC-FID). The quantification of fatty acids (FA) revealed that for most of the found fatty acids there was no significant difference (p > 0.05) between raw milk and pasteurized milk. However, it was found significant differences for 21 of the 26 analyzed fatty acids (p > 0.05) for the raw and sterilized milks, including the predominant isomer of the conjugated linoleic acid (CLAc9t11) of the milk. This fact evidences the successive action of heat treatments on milk lipid profile.