Research On Lipase-Catalyzed Synthesis Of Structured Lipids

Oil is the highest energy nutrients. Rapeseed oil spreads widely in China. The research take rapeseedoil as a raw material to produce structured lipids of lower energy which maintain raw partial essential fattyacids. The research take rapeseed oil and caprylic acid as substrates, take 1, 3-directional lipase-LipozymeRM IM as catalyst to produce structured lipids, and study influence factors which affect acidolysisreaction. Including: reaction temperature, reaction time, enzyme load, substrate ratio, organic solvent, etc.The research selects four factors, five levels to design the experiment using regresstion orthogonalsmethod, and has found the optimum condition. Four factors scope respectively are: Reaction temperature(Te), 40-80℃; Reaction time(Ti),3-11h; Substrate ratio(Sr), 1:1-5:1 (fatty acid/oil, mole of ratio); Enzymeload (E1), 4%-12% (by substrate weight). Results show that: (1) Reaction temperature has obviousinfluence to the acidolysis reaction,caprylic acid concent incoporation to the glycerine structure increaseaccording with temperature in the non-solvent system.When temperature surpasses 70℃, caprylic acidcontent begin to drop for the possibility of the lipase lost activation. (2)Enzyme load has direct correlationwith reaction rate, along with enzyme load increasing, the opportunity of substrate contact with lipase isincreasing, the reaction rate speeds up, the interesterification extent of reaction enhances, caprylic acidcontent incoporation to the glycerine skeleton increases.When enzyme load rises to a certain degree,caprylic acid content increases slower which may has relation with hydrolisis strengthen. (3)Reaction timeis also a important factor to caprylic acid insertion, along with the reaction time increases, the reactingsystem finally achieved the dynamical equilibrium, the reaction and back reaction speed is tend toconsistently. (4)Substrate ratio affect reaction rate of interesterification and acyl migration.When substrateratio is smaller than 2:1,caprylic acid insertion increases obviously with substrate ratio,then slower.Theoptimized condition is:Reaction temperature, 67.0℃;Substrate ratio(caprylic:rapeseed oil), 3.2: 1(mole ofratio);Enzyme load, 11.8% (by substrate weight);Reaction time, 9.0h.Under this condition,caprylic acidcontent in structured product is above 12.4%.The structured product is clear light yellow liquid, is samewith the ordinary oil smell, and has the good solubility with the raw material oil.The thermal propertiesexperiment indicate that the calorific value of the structured lipids is lower.This modified method canobtain the specific goal product with few by-product, reduce the separation purification operation, andresponse condition temperate, the craft is simple, also the reaction system do not need organic solvent.Thisresearch has important value for oil deep processing technology.