Caffeic acid-integrated biopolymer systems: Advancing sustainable active packaging for food preservation.

The urgent need for sustainable food packaging solutions has propelled research into biopolymer-based materials enhanced with natural phenolic compounds. Caffeic acid (CA), a plant-derived polyphenol, stands out as a multifunctional modifier capable of addressing key limitations of biopolymers, such as mechanical fragility, moisture sensitivity, and insufficient antimicrobial activity. This review comprehensively explores CA's dual capacity to stabilize colloids and crosslink polymer chains in polysaccharide- and protein-based films, alongside advanced strategies like enzymatic grafting and nanocomposite design to optimize structural integrity, barrier performance, and active functionalities such as UV-blocking and pH-responsive release. Applications in preserving perishable foods-including meats, fruits, and seafood-demonstrate that CA-functionalized films significantly enhance mechanical strength, moisture resistance, and oxidative stability while delivering robust antimicrobial and antioxidant effects. Although covalent grafting outperforms physical blending in sustaining efficacy, challenges persist in thermal stability and scalable manufacturing. Active food packaging combined with CA will focus on release control optimization, material compatibility improvement, cost reduction and regulatory improvement in the future, to promote the expansion of natural and safe preservation technology to multiple food categories.