Postbiotics as Biochemical Agents in Functional Foods: Mechanisms, Stability, and Health Implications

Postbiotics, defined as preparations of inanimate microorganisms and their metabolites that confer health benefits to the host, have emerged as promising agents in functional food science and biomedicine. Unlike probiotics, postbiotics offer enhanced safety, improved stability, and compatibility with various food processing technologies. This review explores the biochemical mechanisms underlying postbiotic activity, focusing on key metabolites such as short-chain fatty acids, bioactive peptides, and microbial cell wall components. These compounds interact with host receptors to modulate immune responses, reinforce intestinal barrier integrity, and influence systemic metabolic regulation. The stability of postbiotics under thermal and nonthermal processing conditions is critically examined, highlighting factors such as temperature, moisture, oxygen exposure, and food matrix composition that influence bioactivity retention. Analytical techniques, including chromatography, spectroscopy, immunoassays, and in vitro gastrointestinal models, are discussed as tools for evaluating composition, functionality, and bioavailability. The manuscript also reviews the application of postbiotics across dairy, beverages, bakery products, snacks, and processed meats, demonstrating their potential in promoting gut health, metabolic balance, and immune modulation. Strategies such as microencapsulation, advanced packaging, and optimized formulation are emphasized for enhancing stability and delivery. Finally, the paper outlines future research directions involving clinical validation, precision nutrition, and the integration of omics technologies to support personalized dietary interventions. By bridging biochemistry, food technology, and health science, this work provides a comprehensive framework for advancing the development and application of postbiotics in functional food systems.