Natural Antioxidant Biopolymers: Protein-Polysaccharide Conjugates as a Sustainable Strategy to Prolong Food Shelf Life

Food waste, accounting for approximately one-third of global production and contributing significantly to greenhouse gas emissions, poses a critical challenge to modern food systems. Traditional preservation methods, relying on synthetic antioxidants and petroleum-based plastics, face increasing scrutiny due to health and environmental concerns. This review systematically evaluates research from ​​2015-2026​​ on protein-polysaccharide conjugates as sustainable, bio-derived alternatives for food preservation. We analyze their antioxidant mechanisms, the influence of structural characteristics on performance, and their practical applications. The review covers various conjugation methods (Maillard reaction, enzymatic, physical), characterization techniques, and real-world food applications, with a focus on distinguishing synergistic improvements from additive effects. Findings consistently demonstrate that covalent conjugation generates novel antioxidant mechanisms, such as exposing hidden amino acids, forming potent radical-scavenging melanoidins, and developing 3D networks that enhance metal chelation. These conjugates typically outperform physical mixtures by 1.5 to 2.5 times and have been shown to extend food shelf life by 50-200% in diverse applications like edible films, coatings, and emulsions. Despite their promise, significant hurdles persist, including regulatory ambiguity for Maillard reaction by-products, production costs 2-3 times higher than conventional plastics, and limited industrial validation. This review provides an objective, evidence-based assessment of whether protein-polysaccharide conjugates represent a transformative advance in sustainable food preservation or remain promising technologies yet to fully transition from laboratory to market.