Effects of heat-moisture treatment duration and bean condition on the physicochemical properties of red bean (Phaseolus vulgaris L) starch

Abstract

Phaseolus vulgaris L (red beans) contain starch that is primarily composed of 44.8% amylose and 55.2% amylopectin but exhibit temperature instability despite their dietary prevalence. This study used Heat Moisture Treatment (HMT) to improve starch attributes in red beans, testing the effects of 4, 5, and 6-hour treatments at 110°C on both fresh and dried samples. The results indicated that both the HMT duration and the beans' initial state significantly affected the starch's properties. For fresh beans, the moisture content was reduced from 11.56%±0.54 to 3.04%±0.18, while in dried beans, it decreased from 9.32%±0.94 to 3.81%±0.04. Ash content changed minimally ranging from 1.14%±0.25 to 1.96%±0.02. Bulk density in native fresh and dried starches initially recorded at 0.71 g/mL±0.01 and 0.81 g/mL±0.01, respectively, was observed to decrease after HMT, particularly to 0.51 g/mL±0.01 for dried beans treated for 4 hours. Tapped density varied slightly, reaching up to 0.86 g/mL±0.04. Water activity in both bean types also reduced to 0.42±0.01. In conclusion, HMT significantly enhances Phaseolus vulgaris L starch by lowering moisture, bulk density, and water activity, while maintaining ash content. Further studies should explore the best HMT duration and examine the modified starch's functional attributes.