Table 1. Functional classification and key metabolic mechanisms of food fermentation

Functional class	Microbial action	Key products	Significance	Reference
Enhancement of bioavailability	Proteolysis, lipolysis	Bioactive peptide, amino acid, organic acid	Improving nutrient absorption, reduction of antinutritional factors, functional food development	Liu et al., 2024, Bhattacharjee et al., 2025, Dong et al., 2025, Hamadou, 2025, Singh et al., 2025, Li et al., 2023.
Sensory improvement (taste/flavor)	Heterolactic metabolism	Lactic acid, acetic acid, esther, aldehyde, ketone	Sour and umami taste, aroma formation, ensuring quality consistency	Akpoghelie et al., 2025, Okoye et al., 2025, Aguirre-Garcia et al., 2024, Khubber et al., 2022, Terefe et al., 2022.
Texture variations	Exopolysaccharide and CO2 production	Exopolysaccharide, CO2	Increasing the viscosity of dairy products (creaminess), the bloating of bread, softening of vegetable ingredients	Sawant et al., 2025, Praveen and Brogi, 2025.