The Enzymatic Synthesisof Feruloylated Fatty Acyl Structuredin Ionic Liquids

As green solvents, ionic liquids have strong solubility to phenolic substances. However,ionic liquids have certain protective effects on enzyme at high temperature, which isdifferent from methanol and dimethyl sulfoxide to make enzyme deactivation, Therefore, inthis study, ionic liquids, with different anions and cations, were used to enzymatic synthesisof glycerol ferulate and feruloylated monoacyl-and diacyl-glycerols, And the effects ofreaction factors, such as temperature, were also discussed.Three series ionic liquids, based on dialkylimidazolium cations associated with PF-6、TF2N-、 BF-4anions were studied for glycerol ferulate synthesis, and EMIMTF2N was thesolvent. The optimum conditions using one-factor and response surface methodology forenzymatic synthesis of glycerol ferulate were as follows: reaction temperature80oC,40mg/mL enzyme load (relative to the total substrates), substrate molar ratio (EF/glycerol)of1.4:1,5.0h. Under the optimum conditions, EF conversion FG yield were99.47±0.3%and65.94±0.87%, respectively. Besides, the value of Ea calculated by the Arrhenius lawwas41.4kJ/mol what was slightly lower than other Ea values of lipase-catalyzedesterification, indicted EMIMTF2N were able to enhance the reaction.With enzyme as catalyst, the differences between the esterification (FG and oleic acid)and the transesterification (FG and soybean oil) in ionic liquids were compared.C10MIMPF6was the best solvent for lipase-catalyzed reaction between FG and oleic acid.C12MIMPF6was the best for the transesterification.Lipase-catalyzed esterification of FG and oleic acid in C10MIMPF6was investigatedusing one-factor and response surface methodology. The optimum conditions were asfollows: reaction temperature90oC,20mg/mL enzyme load (relative to the whole system),substrate molar ratio (oleic acid/FG) of2.0:1,8h. Under the optimum conditions, FGconversion and FMAGs+FDAGs yield were98.9±0.91%and88.92±0.63%, respectively.thevalue of Ea calculated by the Arrhenius law was75.43kJ/mol what was slightly higher thanother Ea values of lipase-catalyzed esterification. The viscosity of C10MIMPF6may be thereason.Lipase-catalyzed transesterification of FG and soybean oil in C12MIMPF6was studiedusing one-factor and response surface methodology. The optimum conditions were as follows: reaction temperature90oC,45mg/mL enzyme load (relative to the whole system),substrate molar ratio (soybean oil/FG) of2.5:1,11h. Under the optimum conditions, FGconversion and FMAGs+FDAGs yield were94.29±0.72%and83.79±0.95%, respectively.Compared with lipase-catalyzed esterification between FG and oleic acid, thetransesterification of FG and soybean oil also had the following advantages: short reactiontime, low by-product, and so on. However, unlike oleic acid, soybean oil had more potentialto industrial application for its lower price and broader source.