Effect of white kidney bean extracts on estimated glycemic index of different kinds of porridge

The low glycemic index (GI) foods can be particularly effective for diabetics to help keep their blood sugar levels under control. The α-amylase inhibitor from white kidney beans could inhibit the mammalian α-amylase and thus lower the estimated GI (eGI) of high-GI food. In this study, the inhibitory effect of white kidney bean extracts on α-amylase was evaluated, and low-eGI instant porridge with white kidney bean extracts was developed. By adding white kidney bean extracts to 43.2 U/g starch, the eGI of rice porridge, oat porridge, barley porridge, and lotus seed porridge were reduced from 85.18, 55.57, 65.21, and 56.21 to 45.01, 30.41, 42.23, and 20.48, respectively. Since the white kidney bean extracts was heat sensitive, ultra-high pressure (UHP) was used to replace thermal pasteurization in protecting the activity of white kidney bean extracts in instant porridge. With UHP (600 MPa) treatment, no significant change in the eGI of rice porridge (eGI = 45.01) was observed, and the microbial population remained under 1.5 log10 CFU/mL when the rice porridge was stored at 4 °C for 30 d. These findings may support the view that UHP treatment can be potentially used in the production of commercial low-GI porridge with white kidney bean extracts.