Sakshi Jasrotia, Sonali Gupta, Yashoda Malgar Puttaiahgowda, Anna Baborski
Microbial contamination remains a critical challenge that contributes to food spoilage, safety hazards, and substantial global food loss. In response to escalating environmental and health concerns, the packaging sector is undergoing a paradigm shift from petroleum-derived plastics to biodegradable materials with active protection. Among these, polylactic acid (PLA) has emerged as a flagship biopolymer owing to its renewability and composability; however, its inherent brittleness, limited thermal endurance, and weak moisture barrier continue to constrain its commercial viability. This review delineates recent advancements in multifunctional PLA-based nanocomposites engineered with bioactive and metal-derived nanofillers, such as chitosan, silver, zinc oxide, and essential oils, to achieve synergistic enhancement of antimicrobial, mechanical, barrier, and thermal performance. The underlying antimicrobial mechanisms, including reactive oxygen species (ROS) generation, cell membrane disruption, and electrostatic interactions, were critically analyzed to elucidate the structure-function relationships. Emerging fabrication strategies, including electrospinning, reactive extrusion, and solvent casting, are discussed in terms of their precision, scalability, and potential for tailoring surface bioactivity. Furthermore, the integration of intelligent sensing and responsive functionalities for real-time microbial detection is highlighted as a frontier in active packaging. Although notable progress has been made in extending the shelf life of perishable foods, challenges concerning nanoparticle migration, toxicological safety, regulatory compliance, and industrial scalability persist. Future research should focus on eco-friendly nanoparticle synthesis, robust in vivo antimicrobial validation, and comprehensive life cycle assessments to enable the commercial translation of next-generation PLA nanocomposite packaging.