Effect of coupled temperature-humidity drying on multi-scale structure and in vitro digestibility of corn resistant starch.

This study investigates the effects of varying drying temperatures and humidity levels on the molecular structure and digestive properties of resistant starch (RS). The RS content of 60/95 (temperature/relative humidity) sample was 45.39%, significantly higher than that of all other groups. This sample also exhibited the highest crystallinity at 45.73%. The hydrolysis curves for all RS samples showed a gradual increase from 0 to 180 min, with 60/95 demonstrating the lowest hydrolysis rate. High-temperature and high-humidity drying conditions promoted the development of a more complete B-type crystalline cell structure, forming a denser multi-crystalline phase that enhanced resistance to enzymatic digestion. Conversely, the crystal form of 80/95 transformed from type B to type A, achieving the highest long-range order (IR 1047/1022 = 0.978). However, the A-type crystal structure of 80/95 exhibited defects, with loosely arranged grains. This research provides novel insights and processing strategies for the production of RS with improved functional properties.