Roasting-Induced Changes in Bound Phenolics and Their Contribution to Antioxidant Activity in Barley Malts

Background/Objectives: This study investigated the effects of different roasting levels on bound phenolic composition and antioxidant activity in barley malts. Methods: Bound phenolics from raw, fried, and dark malts were characterized using UPLC-Q-Orbitrap HRMS/MS combined with multivariate analysis. Potential antioxidant-active compounds were screened by DPPH/AAPH-incubating UPLC-DAD and further evaluated by in vitro antioxidant assays. Results: A total of 44 bound phenolic compounds were tentatively characterized. Distinct differences in bound phenolic profiles were observed among the three malts, with raw malt exhibiting relatively higher levels of bound phenolics. PCA analysis revealed compositional differences among samples. Activity-guided screening identified epicatechin gallate, trans-ferulic acid, and cis-ferulic acid as compounds exhibiting pronounced radical-scavenging activity, which was further supported by in vitro assays. Conclusions: Different roasting levels were associated with changes in bound phenolic composition and antioxidant properties of barley malts, providing insights into the relationship between thermal processing and the functional quality of malt-based products.