The selectivity of Novozym 435, an immobilized Candida antarctica lipase B toward linoleic (LA), conjugated linoleic (CLA), and pinolenic acids (PLA) was investigated in the esterification of glycerol with an equimolar (27.3 mol% each) mixture of the fatty acids (FAs) in a solvent‐free system to prepare triacylglycerols (TAGs) with anti‐obesity effects. The maximal TAG content of 98.9 wt% was achieved under the following conditions: temperature, 70°C; reaction time, 24 h; glycerol‐to‐FA mixture molar ratio, 1:3; enzyme loading, 10 wt% of total substrates; vacuum level, 0.4 kPa. During the initial phase of the reaction, Novozym 435 showed pronounced selectivity in the order of PLA > CLA > LA; however, no significant difference in the selectivity of Novozym 435 toward the three FAs was observed after the reaction plateaued. Novozym 435 showed the significant selectivity toward PLA over CLA and LA at the sn‐2 position of TAGs throughout the reaction. The resulting TAGs had the same total content (∼27 mol% each) of the three FAs. However, the LA, CLA, and PLA contents at the sn‐2 position were 27.7, 24.7, and 30.3 mol%, respectively, indicating that unlike LA, CLA, and PLA were unevenly distributed on the glycerol backbone of the TAGs. Practical applications: CLA and PLA have received much attention because of their anti‐obesity effects. Structured TAGs containing both CLA and PLA not only maintain the health benefits of each but also may provide several advantages (e.g., enhanced oxidative stability, reduced incidence of off‐flavor) to both for food applications compared to the free FA forms. The selectivity of a lipase toward FAs used as substrates for the lipase‐catalyzed synthesis of structured TAGs affects the composition and positional distribution of FAs in the resulting structured TAGs. The present study reports a new finding about the selectivity of Novozym 435 toward LA, CLA, and PLA which are all C18‐unsaturated FAs, in the esterification of glycerol with the FAs to prepare structured TAGs containing both CLA and PLA. Novozym 435‐catalyzed esterification of glycerol with an equimolar mixture of linoleic, conjugated linoleic, and pinolenic acids.

The positional distribution pattern of fatty acids (FAs) in the triacylglycerols (TAGs) affects intestinal absorption of these FAs. The aim of this study was to compare lymphatic absorption of pinolenic acid (PLA) present in structured pinolenic TAG (SPT) where PLA was evenly distributed on the glycerol backbone, with absorption of pine nut oil (PNO) where PLA was predominantly positioned at the sn-3 position. SPT was prepared via the nonspecific lipase-catalyzed esterification of glycerol with free FA obtained from PNO. Lymphatic absorption of PLA from PNO and from SPT was compared in a rat model of lymphatic cannulation. Significantly (P < 0.05) greater amounts of PLA were detected in lymph collected for 8 h from an emulsion containing SPT (28.5 ± 0.7% dose) than from an emulsion containing PNO (26.2 ± 0.6% dose), thereby indicating that PLA present in SPT has a greater capacity for lymphatic absorption than PLA from PNO.

This study aimed to compare lymphatic absorption of conjugated linoleic acids (CLAs) in the triacylglycerol (TAG) or free fatty acid (FFA) form and to examine the antiobesity effects of different doses of CLAs in the TAG form in animals. Conjugated linoleic TAGs (containing 70.3 wt% CLAs; CLA-TAG) were prepared through lipase-catalyzed esterification of glycerol with commercial CLA mixtures (CLA-FFA). Lymphatic absorption of CLA-TAG and CLA-FFA was compared in a rat model of lymphatic cannulation. Greater amounts of cis-9,trans-11 and trans-10,cis-12 CLAs were detected in the collected lymph from a lipid emulsion containing CLA-TAG. This result suggests that CLA-TAG has greater capacity for lymphatic absorption than does CLA-FFA. The antiobesity efficacy of CLA-TAG at different doses was examined in mice with diet-induced obesity. A high-fat diet (HFD) for 12 weeks caused a significant increase in body weight and epididymal and retroperitoneal fat weights, which were significantly decreased by 2% dietary supplementation (w/w) with CLA-TAG. CLA-TAG at 2% significantly attenuated the HFD-induced upregulation of serum TAG, but led to hepatomegaly and exacerbated HFD-induced hypercholesterolemia. CLA-TAG at 1% significantly attenuated upregulation of retroperitoneal fat weight and significantly increased liver weight, which was decreased by the HFD. Nonetheless, the liver weight in group "HFD +1% CLA-TAG" was not significantly different from that of normal diet controls. CLA-TAG at 1% significantly reduced serum TAG levels and did not exacerbate HFD-induced hypercholesterolemia. Thus, 1% dietary supplementation with CLA-TAG reduces retroperitoneal fat weight without apparent hepatomegaly, a known side-effect of CLAs in mouse models of obesity.