Extraction and Properties of α-Amylase Inhibitor from Phaseolus vulgaris L.

This study extracted α-amylase inhibitor(α-AI) from Phaseolus vulgaris L. seeds by salting-in process. The extracted α-AI was subjected to treatments with different temperatures and pH to evaluate its stability. Then based on the single factor tests and response surface analysis, the extraction process was optimized against particle size(A), material-to-liquid ratio(B), and salting-in time(C) using the inhibitory activity of the extracts against amylase(IC₅₀) as criteria in order to make full of the seeds of old Phaseolus vulgaris L., and increase the value of these Phaseolus vulgaris L. through deep process. The results showed that the α-AI was a heat-resistant protein, which was stable in the pH4~10. The factors affecting the IC₅₀ of α-AI were particle size>material-liquid ratio>salting-in time. The optimal conditions for AI extraction were: Seeds particle subjected to a 60-mesh sieve(with particle size less than 0.3 mm), the mass-volume ratio was 1:12 (g/mL), and the salting time was 7.75 h.The optimal IC₅₀ value for AI from Phaseolus vulgaris L. seeds was 27.036±0.235 μg/mL.