Metabolomic Insights into Traditional Cereal-Based Fermented Foods: Nutritional, Functional and Microbial Perspectives

Traditional cereal-based fermented foods occupy a central place in dietary patterns across Asia, Africa, Europe and the Americas, offering improved digestibility, extended shelf life and distinctive sensory qualities. Advances in metabolomics, particularly gas chromatography–mass spectrometry, liquid chromatography–mass spectrometry and nuclear magnetic resonance spectroscopy, have transformed the capacity of researchers to characterise the biochemical transformations that occur during spontaneous and starter-driven cereal fermentation. This review synthesises current knowledge on the metabolomic dimensions of cereal-based fermented foods, drawing on sourdough breads, South Asian batters such as idli and dosa, African beverages including mahewu, togwa, boza and ogi, and other regionally significant products. The nutritional consequences of fermentation are examined with attention to protein and amino acid modification, mineral bioavailability, vitamin biosynthesis and starch remodelling. Functional metabolites generated through microbial metabolism, including gamma-aminobutyric acid, bioactive peptides, phenolic derivatives and exopolysaccharides, are discussed alongside their proposed physiological relevance. The interaction between fermentation microbiota and the resulting metabolome is considered in relation to gut health and host metabolic outcomes. Safety dimensions, notably the formation of biogenic amines and the persistence of mycotoxins, are appraised as necessary counterpoints to the functional narrative. The review closes by identifying methodological gaps, in particular the underrepresentation of multi-omics integration and standardised metabolomic workflows for indigenous fermented cereals, and by outlining priorities for future research capable of translating metabolomic findings into practical applications for food quality control, nutrition policy and product innovation.