Biodegradable Polyester–Starch Composite Films Functionalized with Phenolic Compounds: Advances, Challenges, and Prospects for Sustainable Active Packaging

The growing demand for sustainable food packaging has intensified interest in biodegradable materials that can reduce environmental impact while preserving food quality. Among these materials, biodegradable polyester–starch composite films functionalized with phenolic compounds have gained attention as promising active packaging systems. They combine the melt processability and structural stability of polyesters, such as poly(lactic acid) (PLA), poly(butylene adipate-co-terephthalate) (PBAT), poly(butylene succinate) (PBS), and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) with the renewability and biodegradability of starch and the antioxidant, antimicrobial, and UV-protective functions of phenolics, such as ferulic acid, quercetin, tea polyphenols, and anthocyanins. This review discusses recent advances in the selection of biodegradable polyesters, starch and thermoplastic starch blending, phenolic incorporation strategies, and their effects on compatibility, morphology, mechanical strength, barrier properties, optical behavior, release, and active packaging functionality. The characteristics and functionality of these films are governed not only by the individual components but also by phase morphology, interfacial interactions, phenolic location, processing conditions, and release control. Key challenges include polyester–starch incompatibility, TPS moisture sensitivity, phenolic stability during melt processing, migration safety, controlled release, and industrial scale-up. Collectively, biodegradable polyester–starch films functionalized with phenolic compounds represent a promising route for developing next-generation sustainable active packaging and may contribute to circular economy approaches.