Sodium alginate–gum Arabic microcapsules for corn antioxidant peptides: Wall matrix characteristics, controlled gastrointestinal release, and digestion-associated antioxidant activity

CAPMs were fabricated using sodium alginate/gum Arabic by ionotropic gelation. • CAPMs achieved 86.18% encapsulation efficiency with favorable powder properties. • CAPMs showed pH-responsive release and zero-order release kinetics. • Encapsulation improved CAP stability and intestinal antioxidant activity. Microencapsulation serves as an effective strategy to enhance the stability, bioaccessibility, and controlled release of food-derived bioactive compounds. In this study, corn antioxidant peptide microcapsules (CAPMs) were fabricated via extrusion-ionotropic gelation using sodium alginate (SA) and gum arabic (GA) as composite wall materials. The physicochemical properties, encapsulation efficiency, structural characteristics, in vitro antioxidant activity, gastrointestinal release behavior, and corresponding release kinetics of CAPMs were systematically investigated. The microcapsules exhibited a high encapsulation efficiency of 86.18%, a mean particle size of 0.70 mm, favorable flowability, low moisture content, and satisfactory aqueous solubility. Optical microscopy and scanning electron microscopy showed that CAPMs retained a relatively continuous and compact structure after freeze-drying, suggesting that peptide incorporation may have contributed to the structural stability of the SA/GA matrix. FTIR, XRD, and UV-Vis confirmed that the peptides were successfully incorporated into the matrix via hydrogen bonding, electrostatic interactions, and physical entrapment, without destroying their primary structure. In vitro digestion revealed that CAPMs exhibited restricted release in the gastric phase but enhanced release in the intestinal phase, with the release profile following zero-order kinetics (R 2  = 0.9559), confirming a sustained-release behavior. Furthermore, CAPMs showed digestion-induced increases in DPPH and ABTS radical scavenging activities and total reducing power. Overall, these findings demonstrate that SA/GA-based microencapsulation effectively improves the digestive stability, controlled release behavior, and functional bioavailability of CAPs, highlighting its promising potential as a delivery system for bioactive peptides in functional food applications.