Characterization and Antimicrobial Activity Assessment of Postbiotic-Loaded Chia Mucilage–Montmorillonite Films Developed for Food Systems

This study presents the development and characterization of chia mucilage–montmorillonite (MMT) films enriched with Lactobacillus sakei postbiotics. The films were evaluated mainly for their antimicrobial properties and practical applicability in food systems. The postbiotic contained 21 phenolic compounds and 60 volatile metabolites that exhibited inhibitory activity against Escherichia coli O157:H7 and Listeria monocytogenes. Incorporation of postbiotics and MMT into chia mucilage significantly enhanced antimicrobial performance. Rainbow trout (Oncorhynchus mykiss) fillets were used as a model food system to demonstrate practical applicability, and their shelf life was extended by 9–15 days compared with controls. These findings confirm the potential of postbiotic-loaded chia mucilage–MMT films as promising bioactive packaging materials for food systems, combining natural antimicrobial activity with improved preservation capacity.