Fermented Citrus as a Functional Food Matrix: Evaluating Probiotic, Prebiotic, and Postbiotic Potential

ABSTRACT Citrus fruits are globally valued for their high concentrations of vitamin C, flavonoids, soluble fibers, and essential oils, yet their use as substrates for fermentation‐based functional foods remains underdeveloped relative to dairy and cereal matrices. Fermentation of citrus substrates can modify native phytochemicals, enhance bioaccessibility, and generate bioactive metabolites that may contribute to gut and metabolic health. However, a recurring conceptual inaccuracy in the studies is the conflation of fermentation microorganisms with probiotics. Not all microorganisms involved in fermentation meet the internationally accepted definition of probiotics, and many fermented citrus products undergo post‐fermentation stabilization steps that eliminate microbial viability, thereby precluding probiotic functionality in the final product. This review critically evaluates the scientific basis for probiotic, prebiotic, synbiotic, and postbiotic potentials in fermented citrus products. Particular emphasis is placed on distinguishing fermentation microbiota from probiotic strains, assessing microbial survival in acidic citrus matrices, examining fiber and polyphenol biotransformation, and evaluating the extent to which fermented citrus can realistically serve as a probiotic delivery vehicle. The review identifies substantial gaps in strain‐specific validation and clinical substantiation, underscoring the need for rigorous characterization before health claims are advanced. Fermented citrus shows promise primarily as a source of prebiotic substrates and fermentation‐derived bioactive compounds, whereas evidence supporting consistent probiotic delivery remains limited and context‐dependent.