Determination of Fatty Acid Composition of Food Containing Short Chain Fatty Acids

Abstract

Because of the high volatility and water solubility of short chain fatty acids and their methyl esters, analysis of the fatty acid composition of food lipids in which they are present is more difficult than that of lipids containing only long chain fatty acids. The GLC analysis of such lipids of small amount (about 100mg) was established in the present study as follows: a lipid was methylated with diazomethane and Na-methylate, and the produced fatty acid methyl esters were extracted in n-hexane. The short chain (413 and 16:0) fatty acid methyl esters were measured by temperature programmed GLC on 15% OV-275 column, and long chain (1424) fatty acid methyl esters by isothermal GLC on a suitable column for the analysis of fatty acid methyl ester such as DEGS. To determine the complete fatty acid (424) composition, these data of fatty acid methyl esters contents were combined by mediation of methyl palmitate amount, since palmitic acid is the major fatty acids in many food lipids. The fatty acid composition of butter fat, margarine (containing milk fat) fat and coconut oil was determined, and the recovery of lipid as total fatty acid methyl esters was 97.6% butter fat, 98.5% margarine fat and 97.9% coconut oil, respectively.