Epigallocatechin gallate-loaded alginate-peanut protein hydrogel beads: Influence of pectin-based crosslinking and chitosan-based coating strategies

Epigallocatechin gallate (EGCG) exhibits potent antioxidant capacity along with multiple health-promoting bioactivities; however, its low bioavailability has limited its practical application. In this study, composite hydrogel beads were fabricated using sodium alginate (SA) and peanut protein isolate (PPI) as the primary matrix materials, and EGCG was encapsulated via two distinct strategies: blending low-methoxy pectin (LMP) with SA for calcium ion–induced multiple cross-linking, and combining quaternized chitosan (QC) with SA through interfacial layer-by-layer self-assembly to create an electrostatic coating. Both aimed to improve EGCG stability during digestion and enhance its functionality. The results demonstrated that the incorporation of LMP and QC both enhanced the mechanical properties of the hydrogel beads ( P <  0.05), with hydrogen bonding and electrostatic interactions serving as the primary forces driving gel formation. LMP addition reduced encapsulation efficiency (EE), whereas QC enhanced it; the highest EE (74.23%) was achieved at 0.5% QC. Under simulated gastrointestinal conditions, the beads demonstrated pH-responsive behavior: EGCG release was slow in gastric fluid (25.1%–44.3%) but increased sharply in intestinal fluid. Overall, QC-modified SA–PPI composite hydrogel beads represent a promising carrier platform with significant potential for targeted intestinal delivery of hydrophilic bioactives such as EGCG.