The weakened 1,3-specificity in the consecutive microwave assisted enzymatic synthesis of glycerides

The nonthermal effect of microwave irradiation (MI) on the 1,3-specificity in the enzymatic esterification of glycerol and caprylic acid in the presence or absence of the solvent was studied, respectively. Comparison on the 1,3-specificity was made between reactions driven by low power consecutive microwave irradiation and conventional heating (CH). For the four assayed lipases, the microwave irradiation did not change but weaken the lipase's 1,3-specificity regardless the form of the lipase employed in the solvent-free medium. Novozyme 435 was then selected for the further investigation to reveal the changing of the 1,3-specificity resulted by varying reaction parameters under consecutive microwave irradiation and conventional heating, respectively. The influence of the molar ratio of the substrates, the initial water dosage, the solvents with different log P, and the power of the microwave irradiation on the 1,3-specificity was investigated. In any circumstance assayed, the consecutive microwave irradiation did not change but weaken the 1,3-specificity of Novozyme 435 in the presence or absence of the solvent.