Postbiotics in Functional Foods: Production, Delivery, Preservation, and Regulation

Postbiotics-defined by the International Scientific Association of Probiotics and Prebiotics (ISAPP) as preparations of inanimate microorganisms and/or their components that confer a health benefit to the host-are attractive from a stability perspective compared to live probiotics. They withstand thermal processing and room-temperature transport and storage and are compatible with low-pH or low-water-activity food products. Despite the promise, the literature is scattered, with no review that integrates evidence from the development pipeline. This review fills that gap. The ISAPP 2021 definition is reviewed, including the practical difficulty resulting from the exclusion of cell-free supernatant (CFS)-based products that represent most of the experimental evidence. Fermentation-based production systems and non-thermal inactivation technologies-high-pressure processing (HPP), pulsed electric fields (PEF), ultrasound, cold plasma, and supercritical CO₂-are compared; non-thermal inactivation preserves the activity of thermolabile bacteriocins and phenolic fractions. Delivery systems such as spray-drying, alginate hydrogel microencapsulation, liposomal nanoencapsulation, and carboxymethyl cellulose (CMC) active packaging are assessed for gastrointestinal survival and food system compatibility. Biopreservation potential is reviewed in meat, seafood, dairy, fresh produce, and fermented foods. The regulatory framework for the United States, European Union, Japan, and India is critically reviewed; "postbiotic" is not an explicitly defined term in 2025. Three priority translational bottlenecks are identified: the absence of standardized potency assays, the lack of cross-class quality benchmarks, and the unresolved conflict between heat-inactivated dairy postbiotics and the Codex Alimentarius live-culture standard. Harmonized regulations and characterization standards are critical needs for postbiotic functional food development.