Enzymatic Interesterification Of Palm Olein Catalyzed By Lipozyme TL IM: Interesterification Rules,and Product Characterization

Enzymatic interesterification catalyzed using sn-1,3 specific immobilized lipase is one of the emerging technologies in the specialty fats industry.Enzymatic interesterification has several advantages over the conventional chemical interesterification method,such that the process has higher flexibility and efficiency,is environmentally friendly and the immobilized lipase can be recycled besides of the lower requirement for substrate's acid value.sn-1,3 specific immobilized lipase Theoretically,the position of the fatty acid at sn-2 remained unchanged when the interesterification is catalyzed using sn-1,3-specific lipase.Nevertheless,in actual catalytic process,modification of the sn-2 fatty acid attributed to acyl migration,has been reported.Not only the specificity of the interesterification process is affected by acyl migration,the physical,chemical and nutritional properties of the final product will also be affected.It is important to study the EIE mechanism and pathways of acyl migration in reactions catalyzed using sn-1,3 specific lipase,which is of great significance to the application of enzymatically directed controlled modification technology for structured lipids(SL)industrial production.In this study,palm olein(POL)was used as the raw material,and the sn-1,3 specific immobilized lipase Lipozyme TL IM was used to catalyze the interesterification modification.The main research results are as follows:(1)The effects of Lipozyme TL IM loading amount,reaction temperature,and reaction time on AMD during the interesterification process in stirring system were explored.The acyl migration degree(AMD)evaluation model was proposed and used.The AMD increased with the amount of lipase loaded,recording the highest AMD of63.41% when 11% of Lipozyme TL IM was added at 80 ?C for 2 h.When the reaction time and temperature was further increased,the AMD remained constant at100%,reaching a completely randomized interesterification.(2)The enzymatic interesterification process is accompanied by the migration of acyl groups,which will change the composition of triacylglycerol(TAG)in POL.The crystallization behaviors,solid fat content(SFC)and thermodynamic properties of the samples also changed accordingly.Higher AMD promoted a random rearrangement of the TAG to obtain tri-saturated TAG and achieved a fast crystallization and the solid state was improved.Hence,the crystal microstructures were observed to be more uniform and was dominated with ?? crystals.(3)The effects of reaction flow rate and reaction temperature in the packed bed reactor(PBR)reaction system on AMD was explored.The difference between the continuous PBR reaction system and the stirring system on the acyl migration was also compared.The acyl migration rules obtained in the stirring system was applied to predict the PBR reaction to provide guidance for controllable continuous production.The occurrence of acyl migration during the interesterification using a PBR was promoted by increasing the reaction temperature or reducing the flow rate,.And,the stirring system can be used to predict the EIE reaction trend and the AMD change rule in the PBR system.(4)Alterations in both the physical and chemical properties were observed in the interesterified fats,which were influenced by the AMD during interesterification.The effects of the reaction time on the catalytic stability of the Lipozyme TL IM were explored and found that with the increase of the continuous reaction time,the catalytic stability of the lipase gradually decreased,and the reaction time was more obvious in the first 50 h.The thermodynamic properties and polymorphism kept stable.Observed by scanning electron microscopy,it was found that the surface morphology of the immobilized carrier became rough with the increase of the reaction time,thereby affecting the catalytic efficiency.