Applications of Gas Chromatography to Food Analysis (IV)

The fatty acids and free fatty acids were extracted from butter and cheese after saponification or directly, and methylated by diazomethane. The methyl esters of fatty acids wereseparated by gas chromatography with Polyethylene glycol 4000 or silicone grease.The branched and straight chain saturatedatty acids with odd- or even-carbon number were identified or presumed by comparison with the retention time of standard substances. In addition the presence of unsaturated C15, C16, C17, C18 and C19 acid were presumed clearly by gas chromatogtaphy of the methyl esters of fatty acids after bromination.It is considered that the fatty acids with odd-number carbon will be freed easier than that with even-number in higher temperature.