Development of rapid-cooking red kidney beans via combined pretreatments: Insights into starch-driven mechanisms

This study investigated the development of rapid-cooking red kidney beans using a combination of pretreatments, including soaking, freezing, steaming, and microwave vacuum drying, with a focus on the starch-related mechanisms responsible for the reduced cooking time. The results revealed that freezing prior to microwave vacuum drying induced the formation of a uniform porous surface structure, which significantly improved water absorption during cooking and increased the degree of starch gelatinization from 9.58 % to 84.32 %. Starch structural analysis showed that the combined pretreatments caused more extensive disruption to starch granules than microwave vacuum drying alone, including the breakdown of crystalline and short-range ordered structures, exposure of hydrophilic groups, and enhanced water-holding capacity. These structural changes led to a significant reduction in gelatinization enthalpy (ΔH), making the cooking time of red kidney bean comparable to that of rice. This study raises valuable insights for the development of quality instant coarse grains.