Structure and Functionality of Fermented Faba Bean: Influence of Particle Size and Rhizopus spp.

This study investigated the influence of particle size and <i>Rhizopus</i> species on the fermentability, structure, and functionality of faba bean (<i>Vicia faba</i> L.) during controlled solid-state fermentation. Split seeds, coarse particles, and 1000-2000 µm fractions were fermented with either <i>R. oryzae</i> or <i>R. oligosporus</i>. Analyses included compositional profiling, SDS-PAGE, FTIR, DPPH antioxidant activity, phytic acid quantification, and rheological yield stress measurements. Particle size strongly affected mycelial growth and matrix structure: coarse particles supported more uniform mycelial networks, particularly with <i>R. oryzae</i>. After 48 h of fermentation, total protein and phytic acid contents remained largely unchanged; however, SDS-PAGE and FTIR results indicated proteolysis and alterations in secondary structure, accompanied by higher antioxidant activity. Rheological data showed significant species-particle size interactions influencing yield stress, with <i>R. oligosporus</i>-fermented samples exhibiting higher yield stress than those fermented with <i>R. oryzae</i>. Overall, these findings demonstrate that optimising particle size and fungal strain combinations can enhance the structural and functional characteristics of fermented faba bean.