Effects Of Sucrose Esters-protein Interaction On The Interesteriifcation Of Oils And Fats Catalyzed By Lipase

The modification of the porcine pancreas lipase by sucrose esters (SEs) in ethanol solutionwas studied, the behavour of interesterification cataylyzed by SEs modified PPLipase insolvent and in solvent free system were investigated, moreover, the kinetics of theinteresterification catalyzed by S1170-PPLipase and S1670-PPLipase were also explored.The modification was completed for40min at30℃, however the suitable conditions forSEs were different. For S370, the optimal conditions were additive amount5%(mass oflipase), the ratio of ethanol to water1:3(v/v). For S570, additive amount5%(mass of lipase),the ratio of ethanol to water1:2(v/v) were the optimal condition. For S770, additive amount15%(mass of lipase), the ratio of ethanol to water1:3(v/v) were the optimal condition. ForS970, the optimal conditions were additive amount20%(mass of lipase), the ratio of ethanolto water1:3(v/v). For S1170, additive amount15%(mass of lipase), the ratio of ethanol towater1:3(v/v) were the optimal condition. For S1670, the optimal conditions were additiveamount5%(mass of lipase), the ratio of ethanol to water1:3(v/v). From thermal stability test,compared with the original lipase, the catalytic activity of the lipases modified by sucroseesters were higher at40℃-80℃, the lipases modified by sucrose esters had better catalyticactivity in the range of40℃-70℃.Taking tea oil and palmitic acid as raw material, the regular pattern of modified enzymecatalyzed interesterification reaction was observed in solvent system. The acyl incorporationof the interesterification catalyzed by PPLipase increased with the additive amount of enzymebefore the reaction was stopped. The acyl incorporation of the interesterification catalyzed bySE modified PPLipases increased with additive amount of enzyme in4h, the reaction reachedbalance at6h, The acyl incorporation were25.0%for additive amount of enzyme15%,20%and25%, the optimal additive amount of enzyme for modification enzyme and PPLipase were15%. At15%of additive amount of enzyme, The acyl incorporation of modification enzymeincreased at50℃,60℃and70℃. The acyl migration of modification enzyme were nothigher at the same acyl incorporation level at50℃,60℃and70℃, comparison to those ofthe interesterification catalyzed by PPLipase.The results of interesterification in free-solvent system, At the additive amount of SEmodified PPLipases15%,20%and25%, the interesterification reached equilibrium at4h, The acyl migration of modification enzyme of additive amount of enzyme15%were smaller at thesame acyl incorporation level. The acyl incorporation of PPLipase increased with the additiveamount of enzyme, the optimal additive amount of enzyme for modification enzyme andPPLipase were15%. At15%of additive amount of enzyme, The acyl incorporation ofmodification enzyme increased at50℃,60℃and70℃. The acyl migration of modificationenzyme were not higher at the same acyl incorporation level at50℃,60℃and70℃,comparison to those of the interesterification catalyzed by PPLipase.The kinetics model of the interesterification of OOO and palmitic acid catalyzed insolvent systems was established according to mass balance. The functions of theconcentration of each component and time, reaction velocity and time were deduced. Theaverage reaction velocity (K) of S1170-PPLipase calculated from the established modelwas1.0x10-4[L2/(mmol, h, g enzyme)]. The average reaction velocity (K) ofS1670-PPLipase was8.0x10-5[L2/(mmol, h, g enzyme)]. The average reaction velocity (K)of PPLipase was1.64x10-5[L2/(mmol, h, g enzyme)]. It predicted the concentration ofsubstrate as equation, and verified the predicted values,in the final findings, The experimentalvalues were compared well with predicted values from the established model.