Optimized Alkaline Hydrolysis for Recovering Ferulated Arabinoxylan Biopolymers from Maize Bran with Antioxidant Functionality

Maize bran is an abundant cereal byproduct and a promising source of ferulated arabinoxylan biopolymers (FAXs). In this study, alkaline hydrolysis was optimized for FAX extraction from maize bran using a design-of-experiments approach evaluating alkali concentration, extraction time, and temperature. Purified FAXs were characterized for their chemical composition, phenolic and ferulic acid content, antioxidant activity, microstructure, and functional properties using GC-MS, HPLC, FT-IR, SEM, and standard antioxidant and functional assays. The FAX yields ranged from 14.7 to 18.9%, producing arabinose- and xylose-rich polymers (A/X ratio 0.68-0.74) with a high proportion of bound ferulic acid. Antioxidant assays (FRAP, ABTS, and DPPH) showed that alkaline-extracted and bound phenolic fractions exhibited substantially higher antioxidant capacity (<i>p</i> ≤ 0.05) than free phenolics, highlighting the importance of phenolic association with the arabinoxylan backbone. The FAX 3 extract also showed high activity in both the alkaline-extracted phenolic compounds (905.0 μg/g TE) and fraction II (286.5 μg/g TE), indicating that specific structural features may contribute to its bioactivity. In addition, FAXs demonstrated high water-holding capacity and favorable emulsifying properties. These results support the recovery of maize bran-derived FAXs as functional, antioxidant-active ingredients for food and related applications.