Abstract:Red kidney beans were soaked at different temperatures for different durations to determine the effects of several factors on their water absorption characteristics and kinetics. Low-field nuclear magnetic resonance, Peleg modeling, texture profile analysis, and magnetic resonance imaging were used to analyze changes in the water absorption rate, hardness, volume expansion, Peleg constants, relaxation time, and water distribution of red kidney beans after soaking. The results showed that increasing the soaking temperature increased the water absorption rate of red kidney beans, thereby shortening the time to reach equilibrium. The hardness rapidly decreased in the first 2 h of soaking and slowly increased to a stable state after reaching a minimum. Volume expansion increased with temperature and was positively correlated with the water absorption rate. The relative error of the results simulated by the Peleg model was within 10%, demonstrating the reliability of the model. K1 showed a decreasing trend with increasing temperature. During soaking, three forms of water (bound water, free water, and weakly bound water) were observed in red kidney beans. At the optimal soaking temperature (45 ℃) and time (4 h), the soaked red kidney beans had a moisture content of 56.61%, hardness of 57.80 N, and volume expansion of 122.22%. These results provide a reference for the processing and utilization of soaked red kidney beans.
