Optimization of ultrasonic-assisted compound enzymatic hydrolysis process of corncob pretreated with organic acid
The purpose was to destroy the tight structure of corncob lignocellulose for enzymatic hydrolysis and fermentation.The opti-mum organic acid and its concentration were determined by screening experiment firstly.Then the optimal composition and ratio of hy-drolases for corncob were determined by compound enzymatic hydrolysis experiment.Finally,the optimal pretreatment process was op-timized by response surface experiment.The results showed that the optimum process of enzymatic hydrolysis of corncob pretreated with 10%maleic acid was as follows:the liquid-solid ratio of 25∶1,ultrasonic power of 310 W,and ultrasonic treatment time of 34 min at 71℃,and the residue was hydrolyzed with cellulase,β-glucosidase and xylanase(1∶2∶1)for 48 h at pH 4.8 and temperature 50℃.Under this condition,the yield of reducing sugar was 34.49%,which was close to the cellulose content in corncob.The method was proved to be stable and reliable,and could provide preliminary technical support for ethanol production from corncob by fermenta-tion.
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