Enhanced nutritional profile of dehulled peas through fungal fermentation: Impacts on protein, starch, saponins, and total phenolic content

Abstract

Dehulled peas (DHP) are increasingly popular in food applications, but their integration in food products is limited due to high starch and fiber causing gelling and aggregation during cooking. Additionally, DHP contains saponins (secondary metabolite), contributing to bitter flavors, yet they also hold health benefits. We hypothesize that fungal fermentation could enhance DHP nutritional profile and integration into food products. This study evaluated the effects of six fungal organisms (Aspergillus niger [An], Aspergillus oryzae [Ao], Aureobasidium pullulans [Ap], Neurospora crassa [Nc], Rhizopus microspores var. oligosporus [Ro], Trichoderma reesei [Tr]) on DHP over 120 h of submerged fermentation, evaluating total phenolics, starch, saponins, crude proteins, and overall mass balance. Results from the study demonstrated notable changes post-fermentation, including increased overall protein content and solubility, decreased starch content, reduced overall mass recovery, and elevated levels of total phenolics and saponins. Filamentous fungi exhibited a significant reduction in starch content, contributing to a substantial reduction in mass recovery (31%–60%) compared to the control. Unexpectedly, saponin concentrations increased (1.5 to 3 folds) during fermentation, possibly attributed to the breakdown of the substrate matrix and release of bound saponins. Total phenolic levels varied among microorganisms, with An and Nc demonstrating the highest increases (6 to 10 folds) as compared to the control. Overall, these findings point to fungal fermentation as a tool for adding value to yellow peas and other crops facing similar processing challenges. Further research is warranted to understand the health impacts and value of these enhancements.