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.

Functional beverages are increasingly used as a medium for targeted nutritional intervention, but liquid matrices present limitations that free bioactives frequently fail to overcome, such as precipitation, oxidation, and degradation during storage and gastrointestinal transit. This review explores the delivery systems that overcome these limitations in acidic, low-viscosity beverages, including biopolymer nanocarriers, solid-particle-stabilized (Pickering) emulsions, nanoemulsions, co-encapsulation systems and fermentation-derived exopolysaccharides. Beyond simple retention, we propose bioaccessibility (speciated) and sensory acceptability (clarity, mouthfeel, off-notes) as co-primary evaluation endpoints. The compatibility, stability, processing resilience (pasteurization, ultra-high temperature (UHT), high-pressure processing (HPP), pulsed electric field (PEF)), scalability and cost are combined in a comparative decision-support framework, and the sustainability assessment warns against assuming environmental benefits based on bio-based origin alone. Regulatory analysis compares the EU’s statutory nanomaterial framework with functional pathways in the US and UK, framing gastrointestinal dissolution screening as a pragmatic filter rather than a universal barrier. Lastly, we describe novel validation tools, gut-on-a-chip and organoid models combined with AI-powered multi-omics, not as replacements for human studies but as tools to accelerate formulation prioritization. The review proposes a matrix-aware framework for evaluating beverage delivery as a decision-governed translation problem that encompasses efficacy, acceptability, sustainability, and regulatory viability.