This study explored the effects of wheat bran arabinoxylan (AX) of various molecular structures on the functional and in vitro digestibility of wheat starch. AX was separated with sequential ethanol precipitation into different fractions (L-Fra and H-Fra), followed by acidic treatment at varied time to convert L-Fra into different subfractions (H-Sub, M-Sub and L-Sub), and the structural features of AX and its subsequent fractions were compared. The Mw and branching degree of the fractions were decreased in the order of H-Fra (545 kDa, 1.15), L-Fra (86 kDa, 0.35), H-Sub (38 kDa, 0.16), M-Sub (21 kDa, 0.10) and L-Sub (7 kDa, 0.08). The functional properties, such as pasting properties, rheological properties, thermal properties, and their effect on the in vitro digestibility of wheat starch-AX combinations, were closely related to the molecular structures of AX. AX with higher Mw, higher branching degree and phenolic content could better inhibit the starch gelatinization and retrogradation, thus reducing the apparent viscosity and gelling properties of wheat starch. The possible mechanisms can be illustrated as 1) AX could compete for water with starch to inhibit granule expansion; 2) AX could not only adsorb on the surface of starch granules through hydrogen bonds but also entangle with the leached amylose and wrap on the surface of granules; 3) AX contained phenols, leading them to inhibit granule expansion through non-covalent interactions with starch molecules. Overall, this study provides a theoretical basis to improve the quality of wheat starch foods and extend the shelf life of wheat foods.

本研究探讨了不同分子结构的麦麸阿拉伯木聚糖 (AX) 对小麦淀粉功能性和体外消化率的影响。AX 通过顺序乙醇沉淀分离成不同的组分（L-Fra 和 H-Fra），然后在不同的时间进行酸处理以将 L-Fra 转化为不同的亚组分（H-Sub、M-Sub 和 L-Sub），以及比较了AX及其后续馏分的结构特征。馏分的 Mw 和支化度按 H-Fra (545 kDa, 1.15)、L-Fra (86 kDa, 0.35)、H-Sub (38 kDa, 0.16)、M-Sub (21 kDa) 的顺序降低, 0.10) 和 L-Sub (7 kDa, 0.08)。功能特性，如糊化特性、流变特性、热特性及其对体外的影响小麦淀粉-AX组合的消化率，与AX的分子结构密切相关。具有较高Mw、较高支化度和酚类含量的AX能更好地抑制淀粉的糊化和凝沉，从而降低小麦淀粉的表观粘度和胶凝性能。可能的机制可以说明为1）AX可以与淀粉竞争水分以抑制颗粒膨胀；2) AX不仅能通过氢键吸附在淀粉颗粒表面，还能与浸出的直链淀粉缠绕包裹在颗粒表面；3) AX 含有酚类物质，导致它们通过与淀粉分子的非共价相互作用抑制颗粒膨胀。综上所述，本研究为提高小麦淀粉食品品质、延长小麦食品货架期提供了理论依据。