The glyceride structure of swine depot fat

Abstract

Summary and ConclusionsA male pig was reared for three months on a diet containing about 1% fat and 0.2% dienoic acid. The back fat was fractionated into glyceride types by crystallization methods, and the fatty acid composition of each was determined by the spectrophotometric procedure. The relative amounts of the glyceride types almost perfectly fit the hypothesis that there is an oleic acid in the 1 position of each glyceride molecule, that the residual oleic acids are in the 3 position, that the linoleic acid is in the 2 position of the resultant dioleins, and that the saturated acids complete the structure.The GS2U and GSU2 fractions were hydrolyzed by pancreatic lipase. The iodine values of the resultant monoglycerides and free fatty acids indicated that the unsaturated acids are predominantly in the 1 and 3 positions and the saturated in the 2 position. From these data and from previous knowledge of the structure of liver lecithin and of the mechanism of lecithin and triglyceride synthesis, which are discussed, it is postulated that the structure of endogenous animal fat is a resultant of the specificity of the acylating enzyme and of the nature and relative proportions of available fatty acids. The possible influence on depot fat structure of exogenous fat, of the dynamic state of the glycerides, and of the homeostatic mechanism are discussed.Linoleic acid, when fed at a low level, was found to be preferentially deposited and not utilized for energy purposes.

Dietary fat and the fatty acid composition of tissue lipids

“…The rat and dog have their triglyceride fatty acids distributed in an approximately random fashion while in pig triglycerides the saturated fatty acids are predominantly in the 2-position (48)(49)(50)(51)(52). The triglycerides of beef, horse, sheep and human fats resemble vegetable fats in having a degree of selective positioning of saturated fatty acids at 1-and 3-positions.…”

Fatty acid composition and N2 solubility in triacylglycerol-rich adipose tissue: the likely importance of intact molecular structure

“…A similar pattern is observed in wild, non-domesticated swine relatives such as the wild boar and peccary, in which high concentrations of 16:0 are also found on position sn-2 (Mattson et al, 1964). In the adipose tissue of domestic pigs, 18:2n-6 can also predominate at position sn-2 (Reiser and Reddy, 1959). Additionally, unsaturated FA appear to be positioned at sn-3, and 18:1n-9 occurs on both positions sn-1 and sn-3 (Mattson et al, 1964;Reiser and Reddy, 1959).…”

“…In the adipose tissue of domestic pigs, 18:2n-6 can also predominate at position sn-2 (Reiser and Reddy, 1959). Additionally, unsaturated FA appear to be positioned at sn-3, and 18:1n-9 occurs on both positions sn-1 and sn-3 (Mattson et al, 1964;Reiser and Reddy, 1959). Interestingly, other artiodactyls (i.e.…”