Identity of the major triacylglycerols in ovine milk fat

Fontecha, J.; Goudjil, H.; Rios, J.J.; Fraga, M.J.; Juarez, M.

Identity of the major triacylglycerols in ovine milk fat

2005

Fontecha, J. | Goudjil, H. | Rios, J.J. | Fraga, M.J. | Juarez, M.

Ovine milk fat obtained from milk collected from five different flocks was studied to determine its triacylglycerol (TAG) composition using a combination of gas chromatography/mass spectrometry. One hundred and thirty-four molecular species of TAG were identified, but not all could be quantified because some peaks contained more than one species of TAG. Fifty-one per cent of the identified species were trisaturated TAGs, 31% as monounsaturated TAGs and 18% as polyunsaturated TAGs. In terms of chain length, 58 of the TAGs identified (43% of the total) contained short-chain (C4 and C6) fatty acids (FAs), 94 (70%) contained medium-chain FAs (C8-C14) and 112 (84%) were composed of long-chain FAs (C16-C18). One hundred and twenty nine chromatographic peaks were detected. The sum of the 35 peaks, each representing>1 mol% of the TAGs, was 75% of total TAGs. Five peaks, each with>3.5 mol% included trisaturated and monounsaturated TAGs; quantitatively, the largest of these peaks (4.5 mol% of the total TAGs) contained two esterified monounsaturated TAGs with C4: 4,16,18:1 or 4,18,16:1, with the former being present at the highest levels. Comparison of the experimental values of TAG composition in ovine milk with the theoretical values derived from the experimental FA content showed that the distribution of the FAs in the TAGs was not random. The TAGs containing a short-chain FA were synthesized preferentially to those TAGs containing three medium- or three long-chain FAs. Our results for ewes' milk were very similar to those for cows' and goats' milk despite the quantitative differences in the TAG profiles of the different species.

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