Production of medium-chain triacylglycerols from corn oil: optimization by response surface methodology.

Structured lipids (SLs) having long-chain fatty acids at sn-2 and medium-chain caprylic acid (CA, 8:0) at their sn-1,3-positions from corn oil (CO) were obtained and optimized by response surface methodology (RSM) with a three-level, three-factor face-centered cube design. Compositions of triacylglycerol species (TAGs) in SLs were also investigated by reverse-phase high performance liquid chromatography. Lipozyme TL IM from Thermomyces lanuginosa was used for the acidolysis of CO with CA in n-hexane. The effects of substrate molar ratio, enzyme amount, and reaction time on CA incorporation into CO were optimized. The optimum conditions were 13.2% (wt.) enzyme, 3.9:1 caprylic acid/corn oil molar ratio, and 3.1 h reaction time. At optimum conditions, 21.5 +/- 0.8 mol.% caprylic acid containing SLs was obtained. This product was characterized by 50% of triacylglycerol species with equivalent carbon number (ECN) C30, C32, C36, and C38, and 50% of triacylglycerol species with ECN C42, C44, and C46.