Mechanistic Insights into Structurally Tailored WEAX-StarchInteractions: Differential Inhibition of A- and B-Wheat StarchDigestion

Abstract To investigate structural modifications of water-extractable arabinoxylan (WEAX) on wheat A- and B-starch digestion, high- and low-molecular weight WEAX were enzymatically tailored to remove di- or monosubstituted C3 arabinose residues (LD/HD, LM/HM). Tailor-made WEAX formed starch complexes via hydrogen bonding and electrostatic interactions. WEAX decreased the A-starch decomposition temperature but increased that of B-starch. Structurally, WEAX reduced crystallinity, order, and helices in A-starch but increased them in B-starch. Single-helix content decreased by 14% and 10% in HM- and LM-A-starch, while increasing by 5% and 9% in HM- and LM-B-starch. All WEAX inhibited starch hydrolysis, with LM exhibiting the strongest effect by reducing A-starch k1 from 0.32 to 0.28 min–1 and C∞ to 77.38% (A-starch) and 73.87% (B-starch). Among the tailored WEAX, removal of monosubstituted C3 arabinose residues exposed more unsubstituted xylan regions and led to stronger inhibition, whereas removal of disubstituted residues resulted in weaker effects due to retained C2 substituents.