Enzymatic synthesis of trans-free structured margarine fat analogs with high stearate soybean oil and palm stearin and their characterization

Abstract

High intake of trans fat is associated with several chronic diseases such as cardiovascular disease and cancer. Enzymatic synthesis of trans-free structured margarine fat analogs from high stearate soybean oil (HSSO) and palm stearin (PS) was optimized using response surface methodology (RSM). The independent variables considered for the design were substrate molar ratio (SR, PS:HSSO, 2–5), temperature (50–65°C), time (6–22h), and enzymes (Lipozyme® TLIM and Novozym® 435). The response was stearic acid incorporation. All linear parameters had a negative effect on stearic acid incorporation except Novozym® 435. Time was not significant but its interaction terms with temperature and SR had significant effect on the response. Desirable structured lipids (SL) containing 11.2 and 8.9g/100g stearic acid were obtained at 50°C, 20h, 2:1 SR with Novozym 435 (SL1) and 57°C, 6.5h, 2:1 SR with Lipozyme TLIM (SL2), respectively. Using optimal conditions, SLs were synthesized in 1L stir-batch reactor and characterized for fatty acid profile, triacylglycerol species, polymorphism, thermal behavior, and solid fat content. The yield for SL1 and SL2 were 87.3 and 94.8%, respectively. Novozym 435 catalyzed SL had desirable fatty acid profile, physical properties, and suitable β′ polymorph for margarine formulation.