Short-chain TAGs Triacylglycerols

The abundance of fatty acids in triacylglycerols (TAG) can be determined by conversion of the acyl groups into tertiary alcohols on reaction with an alkyl Grignard reagent, followed by chromatographic separation. The method was found to be of advantage over saponification and conversion to a methyl ester, especially in the determination of short-chain fatty acids, which suffer losses by volatilization. ... 

Butterfat is a mixture of more than 100,000 different triacylglycerols (TAGs) with a melting range from -40 to +40°C (109). About 400 different fatty acids (FAs) are present in butterfat, 25% of which were short-chained and 45% were long-chained saturates (110). Such variety in composition is responsible for butterfat s unique physical properties. 

Milk fat contains a number of different lipids, but is predominately made up of triacylglycerols (TAG) (98%). The remaining lipids are diacylglycerols (DAG), monoacylglycerols (MAG), phospholipids, free fatty acids (FFA) and sterols. Milk fat contains over 250 different fatty acids, but 15 of these make up approximately 95% of the total (Banks, 1991) the most important are shown in Table 19.1. The unique aspect of bovine, ovine and caprine milk fat, in comparison to vegetable oils, is the presence of high levels of short-chain volatile FFAs (SCFFA), which have a major impact on the flavor/aroma of dairy products. Most cheeses are produced from either bovine, ovine or caprine milk and the differences of their FFA profile are responsible for the characteristic flavor of cheeses produced from such milks (Ha and Lindsay, 1991). 

L = long chain fatty acids, M = medium chain fatty acids, S = short chain fatty acids, MAG = monoacylglycerols, DAG = diacylglycerols, TAG = triacylglycerols. Substrate specificity to acylglycerols. 

Fats are composed primarily of triacylglycerols (TAG). A TAG consists of three fatty acid residues esterified to a glycerol (three-carbon sugar alcohol) backbone at specific locations known as sn-1, sn-2, and sn-3. Fatty acid residues exist in a wide variety of forms, including short and long chain, saturated and unsaturated, odd or even carbon number, tmns- or cis-, linear or branched, as well as any combination thereof (21). TAG variety in a fat system is very large, as there are potentially hundreds of different fatty acid residues and their isomers available for reaction at any of the three sn-positions. 

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