Protein–Polysaccharide Gel Systems for Antioxidant and Antimicrobial Delivery in Sustainable Food Packaging: A Review

Global demand for sustainable food packaging materials has intensified research on bio-based biopolymer systems capable of delivering functional compounds. Among these, protein–polysaccharide gels have emerged as versatile matrices for the incorporation and controlled release of antioxidant and antimicrobial agents. This review examines recent advances in the design and functionality of protein–polysaccharide gel systems for active food packaging applications. Particular attention is given to representative hybrid matrices such as casein/chitosan, gelatin/alginate, and whey protein/pectin systems, highlighting their gelation mechanisms, molecular interactions, and physicochemical properties. Furthermore, the review explores the potential of agro-industrial and marine by-products as renewable sources of proteins, polysaccharides, and bioactive compounds within circular bioeconomy strategies. Current limitations related to stability, scalability, and regulatory compliance are also addressed. By integrating structural, functional, and sustainability perspectives, this work provides a comprehensive framework for the development of next-generation protein–polysaccharide gel carriers for active food packaging.