The influence of protease hydrolysis of lactic acid bacteria on the fermentation induced soybean protein gel: Protein molecule, peptides and amino acids

The purpose explored the influence of protease hydrolysis of lactic acid bacteria and its hydrolysates on the fermentation induced soybean protein gel. The changes of protein molecule, peptides and amino acids after hydrolysis were analyzed. With the extension of fermentation time, the molecules (≤30 kDa) of L. paracasei-gel and L. plantarum-gel increased to 68.8% and 63%, the surface hydrophobicity of protein was increased, internal sulfhydryl groups and soluble proteins were reduced. These results indicated physicochemical properties of protein molecules were changed, small molecular proteins produced by hydrolysis were aggregated through intermolecular forces to promote gel formation. Peptide profiles and amino acid profiles showed that the peptides (≤10AA) of L. casei-gel increased by 3.32%, the peptides derived from 7S protein increased by more than 5%, the hydrophobic peptides and hydrophobic amino acids increased, these enzymatic hydrolysates may form insoluble aggregate through intermolecular forces to promote gel formation.