Abstract:

The activities of alpha-amylase, beta-amylase and limit dextrinase in malt were measured by BPNPG7 method, PNP β-G3 method and pullulan method, respectively. Based on this investigation, the influences of temperature and pH value on the activity of the amylases were discussed and their thermal stability and hydrolysis performance were analyzed. The results showed the optimal reaction temperature for malt alpha-amylase, beta-amylase and limit dextrinase was 70, 60℃ and 55 ℃, and the optimal reaction pH values were 5.5, 5.5 and 5, respectively. The thermal stability of the alpha-amylase was better than that of two other amylases. Malt beta-amylase could retain good thermal stability at 50℃ and 55℃. Comparatively, malt limit dextrinase had poor thermal stability. In addition, these three amylases in malt presented certain relationships between activities at different reaction temperature and reducing sugar content in hydrolysis system.

Key words: malt, amylase, activity, determination, characteristics