Inhibition of cyclodextrins on the activity of α-amylase

alpha-amylase activity influences both flour fermentation process and the quality of the fermented products due to its ability of breaking starch into smaller units. The inhibition of cyclodextrins on alpha-amylase activity was investigated in this paper. Experiment results showed that hydrophobic cavity size was an intrinsic factor during the inhibition processing. Among three types of cyclodextrin (alpha-, beta- and gamma-), beta-type exhibited the most significant inhibitory activity toward alpha-amylase. The optimal inhibitory parameters were indicated to be pH 5.9, concentration of beta-cyclodextrins 1 mmol/L, reaction temperature 45 A degrees C and reaction time 60 min. Results suggested that the endogenous fluorescence of alpha-amylase was inhibited by cyclodextrins. Circular dichroism spectrum indicated that the secondary structure of alpha-amylase, including alpha-helices, beta-sheets and random coils, was changed by cyclodextrins. All the results in this paper aim to provide a further understanding for alpha-amylase in the industry application.