Abstract:

In this study, white kidney bean was used as the raw material to prepare polypeptide with α-amylase inhibitory
activity by enzymatic hydrolysis. The hydrolysis efficiencies of acidic, neutral and alkaline protease for α-amylase inhibitor
(α-AI) activity were compared to determine 3.350 acidic protease as the best enzyme. Using combination of single factor
and orthogonal array designs an enzyme dosage of 3 200 U/g, an initial pH of 2.2 and 60 min hydrolysis at 55 ℃ were found
to be optimal to obtain the maximum α-amylase inhibitory rate of 80.82%. White kidney bean polypeptide derived from
α-AI extract had higher thermal stability than α-AI extract, and the α-amylase inhibitory activity of the polypeptide could be
maintained for a longer time at 85 and 90 ℃. Electrophoretic analysis showed that the molecular weight of white kidney
bean polypeptide was 7.53–9.09 ku.

Key words: white kidney bean albumin, α-amylase inhibitor (α-AI), polypeptide, α-amylase inhibitory activity, thermal stability