In vitro and in vivo evaluation of protein quality, techno-functional and physiological response of fermented Mucuna pruriens and Sphenostylis stenocarpa

Abstract

The identification of promising plant protein sources for food applications requires assessment not only of their compositional attributes but also of their physiological safety. This study investigated the effects of 48 h lactic acid-fermentation on the quality, techno-functional properties and biochemical effects of Mucuna pruriens (VB) and Sphenostylis stenocarpa (AYB) proteins using integrated in vitro and in vivo approaches, compared with soybean. Fermentation increased protein by 24.1% in VB and 31.6% in AYB, enhanced antioxidant activity (DPPH, 36.1–112.0%) and techno-functional properties, and reduced phytate (26–46%), tannins (49–81%), and alkaloids (13–41%) compared with untreated seeds. SDS–PAGE revealed partial hydrolysis of high molecular-weight proteins (135–48 kDa) into lower molecular-weight bands (60–11 kDa), contributing to improved amino acid score (0.56–0.64), in vitro protein digestibility (76.77–90.86%), and protein digestibility-corrected amino acid score (PDCAAS; 44.56–58.24). Rats fed isonitrogenous and isocaloric fermented VB and AYB-based diets for 28 days exhibited improved true protein digestibility (86.90–91.49%), PDCAAS (49.36–57.40%), biological value (85.65–91.63%), and protein efficiency ratio (1.45–2.24), comparable to soybean. Fermented VB and AYB also reduced oxidative stress (malondialdehyde; 70.67–39.97 ng/g protein), enhanced antioxidant enzymes and mitigated hematological and hepatic histopathological alterations observed with untreated seeds. Correlation analysis revealed significant positive associations between in vitro and in vivo protein quality and biochemical indicators. Conclusively, fermentation substantially improved the quality, functionality, and biological safety of VB and AYB, supporting their potential as sustainable alternative protein ingredients for food applications.