Mechanochemistry-driven structural modification of OSA-modified starch via improved extrusion cooking technology: Synergistic enhancement of emulsification and digestive resistance

The preparation of OSA-modified starch often involves heterogeneous reactions, high energy consumption and environmental pollution. To address these issues, this study explored a novel strategy for producing OSA-modified corn starch via a semi-dry process assisted by improved extrusion cooking technology (IECT). The degree of substitution (DS), structure and properties of OSA-modified corn starch, as well as the underlying mechanisms of these changes, were investigated. Results showed that as the screw speeds increased, starch granule morphology became rougher, and the crystalline structure was disrupted. OSA-modified starch exhibited higher peak viscosity and lower gelatinization temperatures. At 300 rpm, the DS of OSA-modified starch prepared via IECT-assisted semi-dry processing increased by 44 ± 0.5 % compared with the conventional method. The resistant starch content increased to 19.6 ± 0.3 %, and it showed better emulsifying activity and stability. This study provides a theoretical foundation for the efficient preparation of OSA-modified starch.