Positional and geometrical isomers of linoleic acid in partially hydrogenated oils

Abstract

The geometrical and positional isomers of iinoleic acid of a partially hydrogenated canola oil-based spread were isolated and identified. Through partial hydrazine reduction and mass spectral studies, c/s-9,tran~13 octadecadienoic acid was identified as the major isomer. Other quantitatively important isomers characterized were c/~9,tran~12; tran~95/~12 and c/s-95/~15. These four were also the major isomers in margarine based on common vegetable oils. A number of minor isomers were detected and some structures identified were tran~9,tran~12; -12; trans-8,cis.13; c/s-8,c/s-13; trans-9,cis-15; trans-10r and c/~9~/s43. The proportions of the various isomers are given for some margarines in the Canadian retail market. The amounts of trans-9,trans-12 isomer in Canadian margarines were generally below 0.5% of the total fatty acids. trans-8,cisKEY WORDS: Ga~iiquid chromatography of trans<Henes, linoldc acid isomers, lipoxidation, margarine fatty acids, octadecadienoic acid isomers, partially hydrogenated oils, trans fatty acids, tran~ octadecadienoic fatty acids, trans-polyunsaturated fatty acids.

Intake of ruminant versus industrial trans fatty acids and risk of coronary heart disease – what is the evidence?

“…Baylin et al [32] explain the high C18:2t biomarker levels by the high consumption of partially hydrogenated soybean oil and margarine in Costa Rica. Reported analyses of TFA in foods, including foods containing partially hydrogenated soy bean oil, show that C18:2t do not exceed 25% of total TFA in North America and Europe [11,40,41]. Ruminant fats contain a similar proportion [6].…”

Influence of the heating temperature on the fat composition of milk fat with emphasis oncis-/trans-isomerization

“…Besides by FAME standards trans D9,trans D12, cis D9,trans D12, trans D9, cis D12 and cis D9,cis D12 (Sigma, St. Louis/Missouri, USA) the identification of trans-C18 : 2-isomers was done according to our earlier studies [35] which essentially were based on the studies of Ratnayake and Pelletier [41] and additionally on the work of Ulberth and Henninger [42].…”

Geometrical isomerization of polyunsaturated fatty acids in physically refined rapeseed oil during plant‐scale deodorization

“…Helium, at a flow rate of 0.8 mL/min, was used as the carrier gas, and 1 mL sample was injected. Retention times of isomeric FAME were established after Ratnayake et al [13][14][15].…”