Study on hydrolysis of potato starch by α-amylase and glucoamylase.

【Objective】 The optimal hydrolysis technology of potato starch by α-amylase and glucoamylase was discussed to provide a reference for reducing the costs of biodiesel.【Method】 The enzymatic hydrolysis of potato starch was carried out by α-amylase and glucoamylase.The enzymatic hydrolysis conditions were optimized with L25(54)orthogonal test and the reaction temperature,substrate concentration,enzyme dosag(m(α-amylase)∶m(glucoamylase)=3∶1) and reaction time were chosen as the factors with the yield of the glucose as determination of indicators;the potato starch hydrolysate was subjected to analysis by HPLC,SEM,XRD.【Result】 The results showed that the optimum conditions were as follows:temperature,substrate concentration,the best enzyme dosage,reaction time and pH were 80 ℃,0.1 g/mL,ratio of enzyme dosage to dry starch of 0.6%,4 h and pH 4.0 respectively,and under this condition,the percent of glucose was the highest,which reached 802.9 g/L.The results of HPLC,SEM,XRD showed that the glucose reached the highest proportion in the enzymatic hydrolyzate.The enzymatic hydrolysis did not destroy the crystal structure of potato starch,the enzymatic hydrolysis just occured on the surface of the potato starch.【Conclusion】 The optimal hydrolysis technology of potato starch by α-amylase and glucoamylase has been found.Therefore,potato starch hydrolysate is a good alternative carbon source,and is superior to glucose for biofuel in industrial processes.