Co‐encapsulation of Macrotyloma uniflorum protein and Pleurotus ostreatus extract in alginate hydrogels: antioxidant potential and phase‐specific bioaccessibility

Abstract BACKGROUND The development of sustainable delivery systems for bioactive compounds is essential to improving their physicochemical stability, bioaccessibility and functional properties in food applications. This study aimed to develop sodium alginate‐based hydrogel beads through ionic gelation for the co‐encapsulation of protein (HP) extracted from germinated Macrotyloma uniflorum seeds and oyster mushroom extract (OME) from Pleurotus ostreatus , thereby creating a hydrogel‐based co‐encapsulation system. RESULTS Alginate hydrogel beads containing horse gram protein–oyster mushroom extract (HP–OME) complexes were successfully fabricated across HP:OME weight ratios of 1:0.1 to 1:0.3 (w/w). The beads exhibited uniform mean diameters (2.03–2.23 mm), whereas precursor colloidal suspensions showed good dispersion stability (polydispersity index = 0.28–0.34) and increasingly negative ζ‐potential values (−21.40 to −30.90 mV). Encapsulation efficiency increased from 61.7% to 91.5% with increasing OME concentration. Results revealed that HPO‐2 (1:0.2 w/w) showed maximum mechanical strength (hardness: 11.23 N), whereas HPO‐3 (1:0.3 w/w) exhibited the highest encapsulation efficiency (61.7% to 91.50%), swelling ratio (6.06g/g) and antioxidant activity based on DPPH (i.e. 2,2‐diphenyl‐1‐picrylhydrazyl), ABTS [i.e. 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid)] and FRAP (i.e. ferric reducing antioxidant power) assays. Fourier transform infrared spectroscopy and X‐ray diffraction analyses indicated non‐covalent protein–extract interactions and structural reorganization of the polymer matrix. Simulated static in vitro gastrointestinal digestion showed limited phenolic recovery under gastric conditions and enhanced phase‐specific bioaccessibility during the intestinal phase. CONCLUSION The co‐encapsulated HP–OME hydrogel beads demonstrated high encapsulation efficiency, enhanced antioxidant functionality and favorable phase‐specific gastrointestinal bioaccessibility, highlighting their potential as a hydrogel‐based co‐encapsulation system with customizable mechanical and antioxidant attributes for functional food applications. © 2026 Society of Chemical Industry.