Fabrication of Chitosan Hybrid Particles with Shrimp Shell Protein Hydrolysate-EGCG Conjugates for Antioxidant Protection in Lipid Systems.

Shrimp shell-derived chitosan and protein hydrolysate-epigallocatechin gallate conjugates (SEC) were used to fabricate hybrid particles (C-SEC) at mass ratios of 1:1, 1:5, and 1:10 using an alkali precipitation method. SEC incorporation significantly enhanced the antioxidant capacity of chitosan particles (p < 0.05). Among the formulations, C-SEC prepared at a ratio of 1:5 (C-SEC-1:5) exhibited the highest antioxidant activities, including DPPH (14.55 mM TE/g) or ABTS (9.80 mM TE/g), or hydroxyl (70.29%) radical scavenging activities, ferric reducing antioxidant power (10.59 mM TE/g), and metal chelating activity (6.37 mM EE/g). The particle size was markedly reduced from 738 nm for chitosan particles (CP) to 112 nm following incorporation of SEC, indicating the formation of finely dispersed hybrid particles. 1H NMR analysis confirmed successful molecular integration of SEC into the chitosan matrix through non-covalent interactions. Thermal analyses revealed altered degradation and transition behavior of the hybrid particles. TGA showed that the principal degradation stages shifted to higher temperatures, whereas DSC showed an increase in transition enthalpy from 370.74 to 2449.60 J/g. SEM and TEM images revealed that the C-SEC-1:5 formed porous, interconnected particle networks with rough surfaces. The selected hybrid particles also showed superior inhibition of Cu2+-induced lecithin liposome oxidation and β-carotene bleaching compared with CP, demonstrating concentration-dependent protection against lipid oxidation. Overall, these findings indicate the potential of C-SEC-1:5 as an antioxidant-based functional ingredient and bioactive delivery vehicle in food and nutraceutical formulations.