Validation of the Determination of Fatty Acids in Milk by Gas Chromatography

Fatty acid methyl esters (FAMEs) in commercial milk samples were analyzed by gas chromatography coupled with flame ionization detection. The saturated fatty acids (SFA) were the most abundant. The major SFA were palmitic acid (16: 0), estearic acid (18: 0), and myristic acid (14: 0). Significant differences (P < 0.500) were found between the amounts of palmitic acid (276 +/- 17 mg g(-1) and 248 +/- 20 mg g(-1)) and myristic acid (95 +/- 5 mg g(-1) and 85 +/- 7 mg g(-1)) in samples. However, no difference was observed for estearic acid (113 +/- 6 mg g(-1) and 114 +/- 11 mg g(-1)). The conjugated linoleic acid (CLA) isomer 18: 2c9t11 was detected in the samples and quantified. However, the differences found between the samples analyzed were not significant (10.4 +/- 0.7 mg g(-1) and 9.9 +/- 0.6 mg g(-1)). The analysis of a certified reference powder milk sample (RM-8435 NIST) gave good recoveries (> 80%), indicating that the method can efficiently determine fatty acids in milk and dairy products.