Sugar was selected for protecting Candida antarctic lipase B entrapped in sol-gel glass matrix.The activities of immobilized CALB influenced by sucrose,glucose,trehalose,xylose and maltose were investigated.The result showed that trehalose,glucose and xylose were the best protector for lipase CALB.By means of infrared spectrometry and differential scanning calorimeter,the protection mechanism of immobilized CALB by xylose was studied.The results showed that xylose bonded with lipase provided significant improvement in the stability of entrapped CALB.
The transesterification of Jatropha oil and methyl acetate to biodiesel catalyzed by a compound lipase was investigated.A 5-level-3-factor central composite rotatable design of the response surface method was used to evaluate the effects of compound enzyme amount,compound enzyme formulation and substrate composition on the yield of biodiesel.The optimum conditions were as follows: enzyme amount 0.27 g,compound enzyme formulation 0.15(mass) N234 and substrate composition of methyl acetate to Jatropha oil 10.10.Under optimum conditions,the actual experimental yield was 74.34%,which compared well with the predicted value of 72.55%.The model based on Ping Pong Bi Bi mechanism with substrate competitive inhibition was proposed to describe the reaction kinetics of the transesterification.
