Enzymetic Transesterification Rules Of Ethyl Feruloyl And Diacylglycerols In Different Reaction Systems

With the increasing attention on the physiological function of ferulic acid, themodification of ferulic acid to maintain its physiological activity and enlarge its applicationhas become an intreasting topic. In the work, the transesterification of diacylglycerols withethyl ferulate (EF) to obtain feruloylated acyl structured lipids in the different system wasinvestigated, which can provide a new route for feruloylated acyl structured lipidspreparation.In the work, solvent-free system, ionic liquids, and organic solvent as reaction mediumwere compaired, and reaction rules of different reaction systems were also found. Reactionthermodynamics and kinetics were also studied.In solvent-free system, the effects of three kinds of diacylglycerols (distearin, diolein,Enova oil) on EF conversion and product yields were investigated, and distearin was selectedas reaction substrate in the next studies. The effects of reaction time, reaction temperature,enzyme load on EF conversion were analyzed. Reaction variables were optimized usingresponse surface methodology as follows: reaction temperature78oC, reaction time24h, andenzyme load14%, reaction system pressure90kPa. Under the optimized conditions, EFconversion was97.6±2.2%, and the lipophilic feruloylated lipids prepared by thetransesterification were consisted of43.2±0.9%feruloylated monoacylglycerols (FMAGs),33.3±1.3%feruloylated diacylglycerols (FDAGs),9.4±1.1%feruloylated glycerol, and11.1±0.7%diferuloylated glycerol, respectively. According to reaction thermodynamics,activation energy of EF conversion, the hydrolysis to form feruloylated glycerol (FG) anddiferuloylated glycerol (DFG), and the transesterification for FMAGs+FDAGs preparationwere caculated as51.1KJ/mol,40.3KJ/mol, and57.8KJ/mol, respectively.In ionic liquid （ILS）system, the effect of different ILS on EF conversion and productselectivity were investigated, and [Emim]TF2N was established as the best medium. Theeffects of reaction time, reaction temperature, and enzyme load on EF conversion and productselectivity were analyzed and optimized using response surface methodology. Under theoptimized conditions (reaction temperature110oC, reaction time21h, enzyme load of15%,substrate molar ratio of1:1, ILS/the total substrate=1:1(w/w), reaction system pressure90kPa), EF conversion was97.9±2.3%. The hydrophilic products were consisted of15.6±1.1%FG,27.9±0.7%DFG, respectively. The hydrophobic products were consisted of 34.7±0.9%FMAGs and21.8±1.2%FDAGs, respectively. According to reactionthermodynamics, activation energy of EF conversion, the hydrolysis to form FG+DFG, andthe transesterification for FMAGs+FDAGs were caculated as44.4KJ/mol,41.4KJ/mol, and59.9KJ/mol, respectively. Enzymatic kinetics parameter, Vm,K BMandK A Mwere4.54mmol/(L·h),0.12mol/L, and0.02mol/L, respectively.In orgnic solvent system, the effect of different organic solvents on EF conversion andproduct selectivity were investigated, and isooctane was established as best organic solvent.The effects of reaction time, reaction temperature, and enzyme load on EF conversion werestudied and optimized using response surface methodology. Under the optimized conditions(reaction temperature67oC, reaction time18h, enzyme load11%, substrate molar ratio of1:1,and isooctane/total substrates=1:1(w/w), atmosphere pressure), EF conversion was79.7±2.1%. The hydrophilic products were consisted of12.3±1.5%FG and4.7±1.6%DFG.The hydrophobic products were consisted of37.8±2.1%FMAGs and22.2±1.5%FDAGs,respectively. According to reaction thermodynamics, activation energy of EF conversion, thehydrolysis to form FG+DFG, and the transesterification for FMAGs+FDAGs were caculatedas65.9KJ/mol,57.7KJ/mol, and72.9KJ/mol, respectively.