Fermented Navy Bean (Phaseolus vulgaris) Products with Improved Nutritional, Antioxidant, and Antihypertensive Potential

This study evaluated the impact of lactic acid fermentation on microbiological and nutritional quality, bioactive compound profile, and bioactive properties of mashed navy beans (MNB). Lactic Acid Bacteria (LAB) viability and microbiological quality of fermented mashed navy beans (FMNBs) were maintained for up to 28 days at 4 °C. Fermentation improved protein quality while reducing trypsin inhibitor activity. Additionally, fermentation enhanced the extractability of phenolic compounds, especially of bound forms. Proteolytic activity during fermentation generated low-molecular-weight peptides enriched in hydrophobic residues. Although antioxidant capacity remained comparable between samples, fermented samples exhibited higher angiotensin-converting enzyme inhibitory (ACE-I) activity (IC50 ACE-I = 0.635 ± 0.043 and 0.413 ± 0.002 mg solids mL−1 for MNBs and FMNBs, respectively). Simulated gastrointestinal digestion enhanced both antioxidant (ABTS•+) and antihypertensive potential. ECA-I inhibition was higher in the fermented sample dialysates (D), with IC50 values of 0.160 ± 0.005 and 0.117 ± 0.003 mg solids mL−1 for MNB-D and FMNB-D, respectively, due to the increased dialyzability of phenolic compounds and the presence of hydrophobic low-molecular-weight peptides in FMNB-D. Furthermore, FMNB-D exhibited competitive ACE-I inhibition. These findings demonstrate that lactic fermentation is an effective strategy to enhance the nutritional and health-promoting properties of legume-based foods.