Effect of kidney bean extract on phytohaemagglutinin activity, functional properties, and the estimated glycaemic index in-vitro

Abstract

This study aimed to decrease the activity of phytohaemagglutinins and kidney bean α-amylase activity in some selected stable foods. Kidney bean α-amylase inhibitors may inhibit mammalian α-amylase, reducing the estimated glycaemic index (eGI). The effect of temperature, pH and protease pretreatment on PHA activity in the crude extract was investigated. Besides, the inhibitory effect of kidney bean extract on α-amylase activity and properties was assessed. Results showed that the PHA activity was decreased to 6.97% from the aqueous extract of kidney beans, while the α-AI activity was retained by 85.89% by acid protease treatment. The extract's α-amylase inhibitory activity remained at 87.37% following simulation in a gastric environment, whereas no effect was observed in a simulated intestinal environment. Adding 3% of the extract decreased the eGI of bread, rice, steamed bread, and steamed corn bread from 65.00, 71.65, 68.17, and 63.41 to 30.69, 39.51, 22.30, and 19.69, respectively. The processing method of crude kidney bean extract examined in this study has significant reference value for the development of kidney bean α-amylase inhibitors and can enhance the intensive processing level and industrial development value of kidney beans worldwide. This discovery suggests that kidney bean extracts can be used to develop foods with a low GI.