Postbiotics and Paraprobiotics as Clean-Label Bioactive Agents for Sustainable Food Packaging: A Review

Postbiotics and paraprobiotics are emerging microbial-derived bioactive agents for sustainable food packaging, offering alternatives to plant extracts and essential oils, which face limitations from resource-intensive extraction, variability, and sensory drawbacks. Postbiotics comprise non-viable microbial preparations and functional metabolites, including organic acids, bacteriocins, exopolysaccharides, enzymes, and peptides. In contrast, paraprobiotics are inactivated cells that retain structural and biological functionality without requiring viability. This review examines their biological activity, incorporation methods, and food applications in active and biodegradable packaging. Both agents exhibit antimicrobial, antioxidant, and anti-biofilm effects against pathogens such as Listeria monocytogenes, Escherichia coli, Salmonella, and Staphylococcus aureus, primarily via membrane disruption, intracellular acidification, competitive exclusion, and radical scavenging. However, their antimicrobial efficacy is highly variable and strongly context-dependent, being governed by the microbial strain inactivation method. These processing variables and matrix interactions must be systematically optimized when integrating these non-viable bioactives into functional packaging systems. Incorporation into biopolymeric matrices such as chitosan (CH), alginate, starch, bacterial nanocellulose (BNC), gelatin, and polylactic acid via solvent casting, dip coating, electrospinning, and encapsulation enhances antimicrobial performance, barrier properties, and oxidative stability. However, mechanical effects depend on the microbial source, inactivation method, and formulation. Real-food trials in meat, seafood, dairy, and produce demonstrate reduced pathogen loads, delayed lipid oxidation, and shelf-life extensions from several days to over two weeks. Key challenges include food-matrix interference, inconsistent terminology and preparation protocols, unclear dose–response and migration behavior, sensory changes, regulatory uncertainty, and scale-up feasibility. Interestingly, postbiotics and paraprobiotics represent a clean-label, sustainable platform for multifunctional packaging. Progress requires standardized production, strain-specific optimization, controlled-release design, migration and safety testing, empirical life-cycle assessments, and regulatory harmonization to enable safer, more sustainable packaging systems that valorize fermentation byproducts and support circular food-system innovation.