Study on the Degradation Patterns and Structure–Activity Relationship of Wheat Arabinoxylan Hydrolysate by Wheat Malt β-1,4-Endoxylanase

This study investigates how wheat arabinoxylan (AX) structure influences its functional properties following enzymatic hydrolysis with wheat malt β-1,4-endoxylanase. Using three types of wheat AX with initial molecular weights of 489.42-602.42 kDa, arabinose-to-xylose (A/X) ratios of 0.49-0.55, and average degrees of polymerization (avDP) of 1223.57-1506.05 as substrates, enzymatic cleavage produced four high-purity fractions with reduced molecular weight (98.63-301.42 kDa), increased A/X (0.60-0.65), and lower avDP (246.59-753.56). Enzyme action led to triple-helix unwinding, especially at low avDP, accompanied by reduced storage modulus. Molecular weight was the key factor affecting water-holding capacity and foam stability, with high-molecular-weight AX showing superior performance due to its intact helical structure and higher viscoelasticity. In contrast, low-molecular-weight AX with high A/X ratios exhibited enhanced interfacial adsorption and free radical scavenging, supported by greater hydroxyl exposure and higher negative charge density (-9.23 mV). Its emulsifying activity and hydroxyl radical scavenging rate increased by 32.95% and 32.02%, respectively, compared to the original AX. These findings demonstrate that enzymatic modulation of AX molecular weight and branching can directionally tune its functionality, providing a theoretical basis for targeted applications in food systems.