Gelatinization and fermentation synergy: investigating the protein digestibility, mineral bioaccessibility and microstructural transformations of black mash beans through Saccharomyces cerevisiae and Lactobacillus spp

Abstract

This study explored the nutritional qualities of black mash bean flour impacted by fermentation, gelatinization and their combination. Protease activity, in vitro protein digestibility (IVPD), and protein solubility were evaluated for both fermented and unfermented black mash bean flour samples. Interestingly, when compared to fermented samples and gelatinized mash bean flour (GMBF), raw mash bean flour (RMBF) showed the highest protein solubility. Due to enzymatic activity and protein hydrolysis, fermentation with Lactobacillus E14 and Saccharomyces cerevisiae MK-157 enhanced protein solubility. Prolonged fermentation timeframes were positively correlated with protease activity and IVPD, suggesting the degradation of complex proteins. The highest levels of IVPD (90.12%) and protease activity (5546.78 U/g) were detected in GMBF fermented by S. cerevisiae MK-157, indicating the impact of fermentation on protein breakdown. The Lactobacillus E14-fermented RMBF exhibited 5521.45 U/g of protease activity and 87.54% IVPD. The mineral content of the fermented samples was substantially greater than that of the unfermented GMBF. The increased calcium, magnesium, potassium, sodium, iron, zinc, and copper levels for the GMBF fermented by S. cerevisiae MK-157 indicated that fermentation facilitated the release of minerals from chelated compounds. Microscopic examination revealed higher protein quantities in the fermented flour as well as hydrolyzed and broken starch granules embedded in the protein matrix. Large mash bean proteins were shown to be proteolyzed during fermentation into smaller peptides by SDS PAGE. Storage proteins were extensively broken down during fermentation with S. cerevisiae MK-157, whereas Lactobacillus E14 displayed a more focused pattern of hydrolysis. The nutritional profile of black mash bean flour was improved by fermentation with Lactobacillus E14 and S. cerevisiae MK-157.

Keywords

• Fermentation
• black mash bean
• protein solubility
• mineral bioavailability
• microbial enzymes