OPTIMIZATION OF LIPASE-CATALYZED ACIDOLYSIS OF SOYBEAN OIL TO PRODUCE STRUCTURED LIPIDS

Abstract

The condition optimization of lipase-catalyzed acidolysis of soybean oil was conducted by using the response surface methodology (RSM). The results showed that when decision coefficient was 98.34%, the optimal conditions for highest caprylic acid (CA) incorporation was: reaction temperature 35.8C, lipase dosage 11.9% (w/w of substrate), substrate ratio 5.7 (oil/CA, mol/mol), water content 15.4% (w/w of enzyme) and reaction time 20.4 h, and under which conditions, the actually measured incorporation of CA was up to 44.9 mol%, very close to the predicted value 45.7 mol%. This indicates that with RSM, we can effectively optimize the reaction conditions of lipase-catalyzed acidolysis of soybean oil to produce structured lipids. PRACTICAL APPLICATIONS In digestion procedure, pancreatic and gastric lipases both have preference for ester bonds located at sn-1 and sn-3 position in triacylglycerols (TGs), and show higher activity towards short- and medium-chain fatty acids (FAs). Dietary TGs are hydrolyzed to sn-2 monoacylglycerols and FAs in the intestine by lipases. Therefore, long-chain polyunsaturated FAs located at sn-2 position may provide sn-2 monoacylglycerols, which are the raw materials in synthesis of TGs in mucosal cells if the dietary fats or oils are MLM- or SLS-type TGs (SLS or MLM are the short-chain or medium-chain FAs located at sn-1 and sn-3 position, while the long-chain FAs are located at sn-2). The short-chain or medium-chain FAs located at sn-1 and sn-3 position are absorbed by the portal vein and rapidly oxidized in the liver as quick source of energy instead of glucose.