Alternations in the multilevel structures of chickpea protein during fermentation and their relationship with digestibility

This study investigated the effects of fermentation on in vitro protein digestibility of chickpeas and their relationship with the variations of multilevel structures of chickpea protein. The results showed that lactobacillus fermentation not only increased the solubility of chickpea protein but also enhanced the hydrolysis of protein during gastric and intestinal digestion by altering the multilevel structures of chickpea protein. The degree of hydrolysis, free amino acid content, and sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) revealed that macromolecule chickpea protein was hydrolyzed during fermentation. Raman and UV spectroscopy scans indicated that the α-helix content increased while the content of β-sheet in chickpea protein dropped significantly after fermentation. As for fermented chickpea protein, the aromatic acid residues were gradually more exposed than the unfermented chickpea protein, and the intramolecular disulfide bond was generally converted to the intermolecular form. Our findings showed that fermentation changed the multilevel structures of chickpea protein, degrading spherical structures into looser states that were more responsible for their effective hydrolysis during digestion. Furthermore, better digestibility of chickpea protein would stimulate the use of chickpea fermentation in food products.