Effect of fine molecular structure of debranched starch on its digestibility

Debranched starch (DBS) has shown promise in the development of slow-digesting starchy foods due to its abundant short-chain glucans (SCGs). However, the effect of its fine molecular structure on digestibility remains unclear. In this study, DBS with varying contents of partially debranched amylopectin (PDA) and debranched SCGs were obtained by adjusting the enzyme content and hydrolysis time, followed by analysis of their multiscale structure and digestibility. The results showed that as the SCGs content increased from 54.16 % to 100 %, the recrystallization rate of DBS significantly increased from 0.19 to 0.62, accompanied by a morphological transition from a worm-like to a spherical structure. SAXS analysis confirmed that high SCGs content led to an ordered and dense DBS structure. Correlation analysis revealed stage-dependent effects of debranching degree and B2 + B3 chain ratio on DBS digestibility: B2 + B3 chains primarily enhanced resistant starch (RS) content when SCGs <85 %, whereas both factors synergistically increased both slowly digestible starch and RS content at SCGs >85 %. These findings suggest that modulating the chain length distribution of DBS is an effective strategy for tailoring its digestive characteristics.