Effect of dominant Lactobacillus and yeast in sourdough on glutenin structure

Using Lactobacillus plantarum Sx9, Lactobacillus sanfranciscensis Gm4 and Saccharomyces cerevisiae Sq7 isolated from the Chinese traditional sourdough as fermentation strains, the effect of the fermentation strains on the solubility, free sulfhydryl content and secondary structure changes of wheat glutenin macropolymer were studied. The results showed that the dissolution rate of glutenin macropolymer increased by 7.06%, 2.47% and 2.47% after 24 h of fermentation by L. plantarum Sx9, L. sanfranciscensis Gm4 and S. cerevisiae Sq7, respectively. During the 6-12 h of fermentation, L. plantarum Sx9 had greater effect on the disulfide bond, and the free sulfhydryl content in fermentation broth increased rapidly from 0.29 μmol/mg to 0.61 μmol/mg. The secondary structure was clearly affected by L. plantarum Sx9 and L. sanfranciscensis Gm4, and after 6 h of fermentation, the content of random coil was recorded almost 0 and all were transformed into β-sheet and β-turn. However, S. cerevisiae Sq7 showed a minimal influence with a small amount of transformation. Therefore, compared with S. cerevisiae Sq7, L. plantarum Sx9 and L. sanfranciscensis Gm4 had better degradation effects on glutenin macropolymer, and L. plantarum Sx9 was the optimal.