Phytochemical-Functionalized Smart Polymer Films: Antioxidant and Antimicrobial Strategies for Next-Generation Active Packaging

The worldwide shift toward sustainable food systems demands packaging solutions that are compatible with the environment, food safety and shelf-life extension. Phytochemical-functionalized smart polymer films have emerged as promising multifunctional active packaging systems with antioxidant and antimicrobial properties. This review critically examines the molecular mechanisms, fabrication strategies, structure-release-performance relationships, applications, and translational challenges of phytochemical-based smart polymer films. Recent advances in incorporating polyphenols, essential oils, curcuminoids, tocopherols, and related bioactives into polysaccharide-, protein-, and bio-based polyester matrices through direct blending, encapsulation, cyclodextrin inclusion, electrospinning, and hybrid nanoparticle systems are evaluated. Phytochemicals can scavenge reactive oxygen species, chelate pro-oxidant metals, and interrupt radical chain reactions, while smart systems enable controlled or stimuli-responsive release triggered by pH, humidity, temperature, or spoilage volatiles. These designs influence antioxidant and antimicrobial activity, oxygen and water-vapor barrier properties, UV protection, and mechanical performance. Applications across meat, fish, dairy, fruits, vegetables, and high-fat foods demonstrate potential for delaying oxidation, suppressing microbial growth, and maintaining sensory and nutritional quality. This review synthesizes phytochemical–matrix–processing–release–performance relationships into a qualitative, application-oriented design framework, emphasizing measurable parameters, formulation-selection criteria, and validation in the intended food and storage environment.