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Recent studies have shown that a 20 % trans,trans conjugated linoleic acid (CLA)-rich soy oil significantly reduces heart disease and diabetes risk factors in obese rats. Furthermore, trans,trans-CLA has been reported to have superior anti-carcinogenic activity than other CLA isomers. Therefore, a more concentrated source of trans,trans-CLA oil would be highly desirable. The objectives of this study were to (1) determine the yield of trans,trans-CLA isomers resulting from photo-irradiation of Tonalin® (BASF Global, Florham Park, NJ, USA) and identify trans,trans-CLA positional isomers; and (2) derive a mathematical model of kinetics of trans,trans-CLA TAG formation from Tonalin®. Fifty-five percent trans,trans-CLA rich oil was obtained in about 140 min when Tonalin® was photo-isomerized with 0.35 % iodine, which is almost three times more than is possible with photo-isomerized soy oil. Photo-isomerization of Tonalin® requires about 2 h, compared to 12 h for photo-isomerization of soy oil. This reaction is a first-order reversible reaction with the forward rate constant (k f) = 13.17 × 10−3min−1 and backward rate constant (k b) = 5.334 × 10−3min−1. The major isomers identified were trans-9,trans-11- and trans-10,trans-12-CLA.

Dear Sir: Predominant isomers of conjugated linoleic acid (CLA), cis-9,trans-11 and trans-10,cis-12 have been shown to improve body composition. In addition, there is preliminary evidence showing that these CLA isomers lower the risk of heart disease and cancer. Recently, trans,trans (t,t) CLA have been shown to decrease LDL cholesterol and liver lipids levels in obese rats. They have also been shown to act as a potent anti-carcinogen in mouse and rat models. However, the lack of commercial availability of t,t CLA isomers has limited its food use, particularly as foodoil triacylglycerides. Furthermore, there is little information on the health benefits of t,t isomers in vivo. This letter reviews the importance of t,t CLA, an overlooked CLA isomer.

A heterogeneous catalysis method to produce 20 % conjugated linoleic acid (CLA)-rich food-grade soy oil in 2 h without solvents or gases was recently developed. The objective of this study was to produce and characterize CLA-rich soy oil margarine relative to a soy oil control and commercial margarine. CLA-rich soy oil was used to prepare margarine. The samples were characterized for firmness, rheology, thermal behavior, solid fat content (SFC) and microstructure and compared with a soy oil control and commercial margarine. The CLA-rich oil margarine firmness and rheological properties were similar to commercial margarine and provided a better texture relative to the soy oil control margarine. However, SFC, droplet size distribution and melting behavior of CLA-rich oil margarine were similar to control soy oil margarine and dissimilar to the commercial product. This suggests that hardness and rheological properties of margarine are not solely dependent on SFC and melting behavior. Lipid composition, polymorphism and microstructure differences in CLA-rich oil margarine may play an important role on the texture and rheological properties. A 7-g typical serving of the CLA-rich oil margarine will provide 0.6 g CLA. Thus five servings will provide 3.2 g/day of CLA and 185 calories/day, which is well within the maximum recommended 700–980 fat calories/day.

A ~20% CLA-rich soy oil with low saturated fat and no cholesterol was produced by photoisomerizing soy oil linoleic acid. The oil is predominately trans,trans CLA, with the oil containing 17% trans,trans CLA. Recent studies have shown that trans,trans CLA-rich soy oil significantly reduces heart disease and diabetes risk factors in obese rats. However, the positional isomerism of these geometrical isomers has not been identified. The objectives of the study were to determine trans,trans CLA positional isomerism of CLA fatty acids in CLA-rich soy oil and determine the resolution of trans,trans CLA positional isomers by silver ion chromatography. GC–MS studies of 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD) derivatives of CLA-rich oil showed that 9,11 CLA and 10,12 CLA were the major positional isomers. These were hypothesized to be the trans,trans CLA isomers, which was confirmed by silver ion chromatography and subsequent GC–FID fatty acid and ATR-FTIR geometrical isomer analysis of the collected fractions. The identification of 9,11 trans,trans CLA and 10,12 trans,trans CLA as the major CLA isomers in CLA-rich oil then allowed the deduction of the synthetic mechanism of the photoisomerism of soy oil linoleic acid to trans,trans CLA.