Mechanism of multiscale structural reassembly controlled by molecular chains during amylase digestion of wheat starch.

The digestive characteristics of wheat starch (WS) are closely related to its structure. However, the mechanisms underlying the multiscale structural evolution and reassembly controlled by molecular chains during digestion are poorly understood. To address this issue, amylopectin of wheat starch (APWS) and amylose of wheat starch (AMWS) were separated and digested in vitro. After digestion, chains in WS with a degree of polymerization (DP) < 12 or DP > 37 were degraded, the double-helix content decreased from 58.65 % to 48.77 %, and many particles were degraded. For APWS, the DP > 36 chains increased, the B-type crystallinity increased to 9.55 %, and the particles were transformed into new aggregated structures. For AMWS, the number of 18 < DP < 270 chains was increased, the double-helix content increased from 19.78 % to 37.92 %, the B-type crystallinity increased from 6.65 % to 19.40 %, and a dense granular structure was formed. Overall, our study confirmed that WS, APWS, and AMWS had distinct multiscale structural reassembly mechanisms during in vitro digestion. The DP > 36 chains in APWS and 18 < DP < 270 chains in AMWS were the primary contributors to the formation of enzyme-resistant multiscale structures. This study can serve as a theoretical basis for designing the WS multiscale structure using molecular chains to improve its nutritional value.