The New Zealand Dairy Industry

1981

Eight samples of milk fat were selected for softening point (SP) range. They were separated into high, medium and low molecular weight triglyceride fractions by silicic acid-column chromatography to enable further separation into triglyceride classes by silver ion adsorption thin-layer chromatography. Correlation between triglyceride class content and SP was low. The molecular species composition of the triglyceride classes was determined and correlated with SP. The best correlations were between SP and some low and some high molecular weight triglycerides of the total fat and the trisaturated (SSS) triglyceride class. Correlation coefficients were determined between SP and mole percentage of individual fatty acids and groups of acids. The highest correlations were between SP and individual short chain-length fatty acids (C 4 -C 10 ) and groupings of short chain-length acids (C 4 -C 10 ) and groupings of long chain-length acids (C 16 -C 20 )-The triglyceride class composition of a sample of milk fat was determined before and after interesterification. Interesterification increased the SP from 316 to 363 °C and produced increased amounts of both low and high and decreased amounts of medium molecular weight triglyceride molecular species in all triglyceride classes. The increases in the amounts of high molecular weight triglycerides were several times greater than the increase in the amounts of low molecular weight triglycerides.

Section: Relationship Betwen Triglyceride Class Content and Spsupporting

confidence: 70%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Relationship between triglyceride structure and softening point of milk fat

1981

“…However, the values for both factories were in most cases higher than previously reported correlation coefficients between groups of fatty acids and SP (Parodi & Dunstan, 1971;Norris et al 1973). Taylor & Hawke (1975a) found that the triglyceride class containing 2 saturated and 1 <rcms-monoene fatty acids (SSM 1 ) accounted for up to 10 % of total triglycerides. Triglycerides with £raws-unsaturation melt at higher temperatures than cis-isomers.…”

Section: Relationship Between the Triglyceride Species Composition Ofmentioning

confidence: 99%

“…The absence of adequate correlation between groups of fatty acids and SP has been attributed to variation in the stereospecific distribution of fatty acids in the triglyceride molecules. However, Taylor & Hawke (19756) and Parodi (1979) have shown that there is little variation in the stereospecific distribution of fatty acids throughout the year. Kartha (1952) studied the melting and solidifying points of mixtures of trisaturated glycerides and non-trisaturated glycerides for a number of fats.…”

mentioning

confidence: 99%

Relationship between trisaturated glyceride composition and the softening point of milk fat

1979

NO relationship was found between the trisaturated glyceride content and the softening point (SP) of milk fat. Inter-esterification of milk fat increased its SP, but did not change the trisaturated glyceride content or the fatty acid composition of the trisaturated glyceride fraction. Inter-esterification increased the amount of both low and high and decreased the amount of medium molecular weight triglyceride species in the trisaturated glyceride fraction. The increase in the amount of high molecular weight triglyceride species was up to 3 times greater than the increase in the amount of low molecular weight triglycerides.The triglyceride species composition of the trisaturated glyceride fraction of milk fat was found to vary seasonally. Excellent correlation was found between SP and groups of low molecular weight triglycerides, groups of high molecular weight triglycerides and some individual triglyceride species. Correlation coefficients were higher than those previously reported between groups of fatty acids and SP.It is common to relate the physical properties of a fat to its fatty acid composition. For milk fat, Hansen & Shorland (1952) could not establish a definite relationship between softening point (SP) and total content of acids which are liquid at room temperature. They considered that SPs were influenced more by the content of short-chain-length fatty acids than by the unsaturated acids. Parodi & Dunstan (1971) reported a negative correlation between SP and mole percentage of shortchain-length fatty acids (r = -0-613) and a positive correlation between SP and mole percentage of long-chain-length fatty acids (r = 0-788). Similar results were obtained by Norris, Gray & Dolby (1973) who found a positive correlation between weight percentage of long-chain-length acids and SP (r = 0-789) and a negative correlation between short-chain-length acids and SP (r = -0-579). The addition of weight percentage cts-unsaturated acids to the weight percentage of short-chain-length acids to give the percentage of acids liquid at room temperature did not improve the value of the correlation coefficient over that found for the short-chain-length acids alone.The absence of adequate correlation between groups of fatty acids and SP has been attributed to variation in the stereospecific distribution of fatty acids in the triglyceride molecules. However, Taylor & Hawke (19756) and Parodi (1979) have shown that there is little variation in the stereospecific distribution of fatty acids throughout the year. Kartha (1952) studied the melting and solidifying points of mixtures of trisaturated glycerides and non-trisaturated glycerides for a number of fats. He reported that 0022-0299/79/1759-4025 $01.00

Stereospecific distribution of fatty acids in bovine milk fat triglycerides

1979

Pancreatic lipase deacylation was used to study the variation in distribution of the fatty acids at position sn-2 of milk fat triglycerides of a series of butters and of the milk obtained from a cow on a restricted feeding regimen. Selected samples were analysed for stereospecific distribution of their triglyceride fatty acids which were found to be esterified in a non-random manner. The percentage of a fatty acid at position sn-3 generally decreased with increase in the chain length of the acid; the reverse occurred at position sn-1. There was no major variation in the stereospecific distribution of fatty acids throughout the year; the variation that did occur was exhibited mainly by the medium chain length acids. Variation was greater at positions sn-l and sn-3 than at position sn-2 and when the proportion of an acid varied at position sn-1 it usually varied at position sn-3 in the reverse manner.For the milk samples it was found that change in triglyceride fatty acid composition was not associated with random increases or decreases of fatty acids at the 3 stereospecific positions. With changing triglyceride fatty acid composition (6:0, 8:0, 10:0, 12:0, 14:0, and 16:0 decreasing and 18:1 increasing) the percentage of 6:0, 8:0, 10:0, 12:0, 14:0 and 16:0 acids at position sn-3 decreased while the percentage of 18:0 and 18:1 acids increased. These changes were compensated for by changes in the opposite direction at positions sn-l and sn-2.