Lipase-catalyed Transesterification Of Coconut Oil For Meduim Carbon Chain Triacylglycerols

This paper focused on the lipase-catalyzed transesterification of coconut oil by caprylic acid or capric acid for medium carbon-chain triacylglycerols(MCT). The reaction conditions were optimized by the univariate tests and response surface methodology(RSM). The fatty acid profile and triacylglycerols composition of raw material and MCT were investigated.The results indicated that monoacylglycerols and diacylglycerol were not detected in raw coconut oil. The coconut oil was rich in C12:0(44.68 %) and C14:0(20.39 %).The content of medium-chain fatty acids(MCFA) was 54.63 %, and 74.12 % in the sn-2 position. The content of MCT was 14.93 % and was mainly composed of La La La(6.89 %)、Oc La La(3.33 %)、DLa La(2.94 %)in raw oil.Immobilized lipase RM IM, resulted in the highest incorporation of caprylic acid and capric acid into coconut oil, was choosed from four screening lipases, Lipozyme RM IM, Lipozyme TL IM, Novozyme 435 and porcine pancreas lipase. In order to explore the selectivity between caprylic acid and capric acid by immobilized lipase RM IM, we took the experiment under the following condition, the substrate mole ratio of oil to fatty acid was 1:3, 4 %(w/w of substrates) enzyme load and 10 %(w/w of lipase) water load. Under this condition, the content of caprylic acid(24.37 %) and MCT(33.85 %) increased by 19.40 % and 18.92 %, respectively. However, the content of capric acid(35.72 %) and MCT(37.46 %) increased by 30.98 % and 22.53 %, respectively. Therefore, we could get that capric acid was easier to react than caprylic acid in lipase catalyzed reaction of four screening lipases.The univeriate tests and optimization tests by RSM were applied to determine the influence of factors and optimized the parameters in transesterification of coconut oil with caprylic acid. This paper also established the regression equation of the content of caprylic acid and MCT, respectively. The optimum reaction conditions for temperature, the substrate mole ratio, enzyme load, water load and reaction time were 68 ℃, 1:6, 8 %, 10 % and 2h, respectively. After a triplicate verification, the main content of caprylic acid(23.11 %) and MCT(35.30 %) increased by 18.14 % and 20.32 %, respectively. The MCT were mainly composed of Oc La La(15.15 %), DLa La(7.90 %) and La La La(7.39 %).Simultaneously, the univeriate tests and optimization tests by RSM were used to research the influnces of parameters in transesterification of coconut oil with capric acid. The regression equation of the content of capric acid and MCT were also established. The optimum reaction conditions were the substrate mole ratio was 1:8, temperature was 46 ℃, reaction time was 8h, enzyme load was 6 % and water load was 15 %. The main content of capric acid(42.31 %) and MCT(50.85 %) increased by 37.57 % and 35.87 % in triplicate verification, respectively. 9 species of MCT were detected in product and the mainly species were DLa D(23.57 %), DLa La(16.88 %), DDD(4.83 %) and La La La(3.30 %).