PREMELTING PHENOMENA IN LONG-CHAIN FATTY ACIDS

1963 ◽  
Vol 41 (5) ◽  
pp. 1188-1196 ◽  
Author(s):  
M. R. Barr ◽  
B. A. Dunell ◽  
R. F. Grant
Keyword(s):  
Fatty Acids ◽  
Nuclear Magnetic Resonance ◽  
Melting Point ◽  
Magnetic Resonance ◽  
Infrared Absorption ◽  
Long Chain Fatty Acids ◽  
Melting Points ◽  
Solid Structure ◽  
Nuclear Magnetic Resonance Spectra ◽  
Long Chain

Nuclear magnetic resonance spectra and the infrared absorption between 700 and 750 cm−1 have been observed at temperatures near the melting points of the even-numbered fatty acids from C18 to C10. The results are interpreted as indicating breakdown of crystalline character and onset of liquid-like motion at scattered points in the solid structure several degrees below the melting point, and increasing in extent as the melting point is approached.

scholarly journals The absorption of stearic acid from triacylglycerols: an inquiry and analysis

2000 ◽  
Vol 13 (2) ◽  
pp. 185-214 ◽  
Author(s):  
Geoffrey Livesey
Keyword(s):  
Fatty Acids ◽  
Body Weight ◽  
Melting Point ◽  
Cocoa Butter ◽  
Stearic Acid ◽  
Short Chain ◽  
Apparent Digestibility ◽  
Long Chain Fatty Acids ◽  
Long Chain ◽  
Chain Fatty Acids

AbstractAlthough stearic acid is a saturated fatty acid, its influence on plasma cholesterol acid other health variables is neutral; possibly owing in part to poor absorption. Reduced absorption of stearic acid from particular triacylglycerols, cocoa butter and novel fats formulated with short- and long-chain acid triacylglycerol molecules (Salatrims) has been attributed to high intakes. However, the circumstances and causes of poor stearic acid digestion from triacylglycerols are unclear; published data were therefore collected and analysed, with emphasis on human studies. Of twenty-eight studies conducted in adults, most are in men (>90%). The assertion that reduced absorption is due to a high intake of stearoyl groups is not supported: dietary intakes of stearoyl of 0·05–0·65 g stearic acid equivalent/kg body weight (cf typical intake of 0·2 g stearic acid equivalent/kg body weight in the Western diet) indicate that the ‘true’ digestibility of stearoyl is 0·98 (SE 0·01) g/g, with apparent digestibility less than this value at low intakes owing to endogenous stearic acid excretion and to inter-publication variation of unidentified cause. The neutral health impact of stearic acid must be due to factors other than availability. Exceptions include cocoa butter, Salatrims and tristearin, for which digestibility is an additional factor. The efficiency with which human subjects digest stearoyl from cocoa butter still remains uncertain, while the digestion of total long-chain fat from this source is 0·89–0·95 g/g, high in comparison with 0·33 g/g for Salatrim 23CA and 0·15 g/g for tristearin in their prepared states. Salatrims contain the highest proportion of long-chain fatty acids that are stearic acid-rich other than tristearin, which is the main component of fully-hydrogenated soyabean and rapeseed oil. Analysis shows that apparent digestibility of stearic acid is associated with stearoyl density within the triacylglycerol molecule and that, in Salatrims, the occurrence of short-chain fatty acids in place of long-chain fatty acids increases this density. Soap formation appears not to be a major factor in the reduced digestion of stearic acid from tristearin under regular dietary circumstances, but both microcrystallinity and reduced digestibility of tri-, di- and monostearoylglycerols appears to be important. Solubilisation of high-melting-point tristearin in low-melting-point oils improves the digestibility of its stearic acid, particularly when emulsified or liquidized at above melting point. However, without such artificial aids, the digestive tracts of the rat, dog and man have a low capacity for emulsifying and digesting stearic acid from tristearin. Reduced digestibility of stearic acid from Salatrim 23CA also appears to be attributable to reduced digestibility of di- and monostearoylglycerols and is particularly due to remnants with the 1- or 3-stearoylglycerol intact after initial hydrolytic cleavage. Short-chain organic acid in Salatrim 23CA, which is readily hydrolysed, leaves such remnants. Unlike tristearin, Salatrim 23CA melts at body temperature and mixing it with low-melting-point oils is not expected to cause further disruption of microcrystalline structures to aid digestibility of its stearoyl groups. The low digestibility of stearoyl in Salatrim 23CA, together with the occurrence of short-chain organic acids in this product, account for its relatively low nutritional energy value (about 20 kJ (5 kcal)/g) compared with traditional fats (37 kJ (9 kcal)/g) and low fat value (<20:37 kJ/kJ; <5:9 kcal/kcal) relative to traditional fats. In part these differences are because of minor effects of Salatrim 23CA on the excretion of other fat and protein, due to the bulking properties of this poorly-digestible fat.

Infrared Absorption Spectra.Some Long-Chain Fatty Acids, Esters, and Alcohols

1950 ◽  
Vol 22 (12) ◽  
pp. 1498-1501 ◽  
Author(s):  
O. D. Shreve ◽  
M. R. Heether ◽  
H. B. Knight ◽  
Daniel. Swern
Keyword(s):  
Fatty Acids ◽  
Infrared Absorption ◽  
Long Chain Fatty Acids ◽  
Long Chain ◽  
Chain Fatty Acids

STUDIES OF THE LIPIDS OF ARTHROBACTER GLOBIFORMIS 616: I. THE FATTY ACID COMPOSITION

1965 ◽  
Vol 11 (2) ◽  
pp. 229-233 ◽  
Author(s):  
R. W. Walker ◽  
I. S. Fagerson
Keyword(s):  
Fatty Acids ◽  
Nuclear Magnetic Resonance ◽  
Fatty Acid Composition ◽  
Melting Point ◽  
Arthrobacter Globiformis ◽  
Mineral Salts ◽  
Nitrate Medium ◽  
Nuclear Magnetic Resonance Spectra ◽  
Branched Chain ◽  
Chain Type

Nearly 96% of the fatty acids of Arthrobacter globiformis 616 cultivated in a glucose – mineral salts – nitrate medium were of the branched-chain type. The fatty acids, identified by melting point and by infrared, mass, and nuclear magnetic resonance spectra were (in order of abundance) 12-methyl tetradecanoic, 14-methyl hexadecanoic, 14-methyl pentadecanoic, hexadecanoic, 12-methyl tridecanoic, and tetradecanoic.

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