Temperature-assisted continuous ethanol gradient fractionation for modulating the structure characteristics and in vitro digestive properties of debranched normal corn starch.

This study aimed to explore how temperature-assisted continuous ethanol gradient fractionation modulates the structural characteristics and digestibility of debranched corn starch. After debranching, five corn starch fractions with distinct molecular weights were obtained by gradual ethanol precipitation under different temperatures. Elevating temperature enhanced the purity of long-chain fractions by suppressing short-chain retrogradation, achieving a long-chain content of 63.63% in the 30% ethanol fraction at 100 °C. Concurrently, the 45% ethanol fraction formed more compact and ordered nanostructures, leading to a significant increase in resistant starch content from 60.42% to 68.05%. Notably, temperature induced a structural reconstruction in short-chain fractions, with the crystallinity of the 75% ethanol fraction increasing from 7.67% to 53.14%. These findings demonstrate that this fractionation strategy provides important insights for designing starch-based ingredients with tailored digestibility and functionality.