Article Review: Influence of Fermentation Duration and Starter Culture on Nutritional Quality and Bioactive Compounds of Fermented Peanut Products

Abstract

Peanut (Arachis hypogaea L.) is an important plant-based protein source containing substantial amounts of lipids, amino acids, phenolic compounds, tocopherols, and other bioactive constituents. However, the nutritional and functional utilization of peanuts is constrained by the presence of antinutritional compounds, limited mineral bioavailability, allergenic proteins, and susceptibility to oxidative deterioration. Fermentation has emerged as a promising biotechnological strategy to improve the nutritional quality, digestibility, functional properties, and bioactive potential of peanut-based products. This review critically evaluates the effects of fermentation duration and microbial starter cultures on nutrient transformation and bioactive compound formation in fermented peanuts. The review discusses the roles of lactic acid bacteria, Bacillus spp., filamentous fungi, and mixed-culture systems in modulating proteolysis, phenolic release, antioxidant activity, γ-aminobutyric acid (GABA) production, phytate degradation, and allergen reduction. Fermentation duration was found to exert dynamic and non-linear effects on nutritional quality, where intermediate fermentation stages generally produced the highest enhancement of digestibility, antioxidant activity, peptide formation, and mineral bioavailability. In contrast, prolonged fermentation frequently resulted in nutrient degradation, off-flavor formation, lipid oxidation, and sensory deterioration. Comparative analysis further revealed that different starter cultures possess distinct optimal fermentation windows and metabolic responses due to variations in enzymatic activity and substrate utilization. Mixed-culture fermentation demonstrated potential synergistic effects through sequential metabolism and broader bioactive compound production, although process standardization remains challenging. This review also highlights current limitations involving fermentation reproducibility, safety concerns, omics integration, and limited clinical validation. Future advances in precision fermentation, artificial intelligence-assisted optimization, engineered starter cultures, and multi-omics approaches may substantially improve the development of fermented peanut functional foods. Overall, controlled fermentation represents a highly promising approach for producing nutritionally enhanced and sustainable plant-based functional foods derived from peanuts.