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We studied the effect of freeze–thaw on isoflavone composition in germinated soybeans, particularly the conversion of aglycones, the isoflavone monomers with high biological activity. Germinated soybeans were frozen at −20 °C, −80 °C, and −196 °C respectively, and then the frozen samples (-20 °C) were thawed at 4 °C, 10 °C, and 25 °C respectively. Results showed total isoflavone increased after germination. Aglycones content increased most at −20 °C, which increased about 24 times. The effect of thaw temperature and time indicated there were approximately 89 % glucosides forms converted to aglycones during freeze–thaw. Isoflavone conjugate-hydrolyzing β-glucosidase (ICHG) activity increased by 65.78 % (25 °C) and 59.14 % (48 h) with freeze–thaw. The cells of germinated soybeans were broken, promoting ICHG contact with glucosides and malonyl-glucosides. These results indicated that freeze–thaw greatly changed the content and profile of isoflavones, resulting in a sharp increase in the content of aglycones.

To understand the formation process of dough with different hydration levels upon mixing and the response of dough rheology, the dynamic evolution of gluten protein was tracked and quantified at morphological, structural, and molecular levels. Both macroscopical and microscopic distribution images showed that partial and full hydration induced quick formation of a more compact gluten network compared with limited hydration. Gluten network in highly hydrated samples was more susceptible to the formation and collapse induced by mechanical force. SE-HPLC results indicated significant depolymerization of glutenin macropolymer (GMP) in fully and partially hydrated samples. Sufficient mixing was accompanied by the increase of ionic and hydrogen bonds, while excessive mixing increased exposure of free -SH. Higher hydration level induced more ordered secondary structure. Correlation and principal component analysis revealed the patterns and dynamics of gluten evolution during dough formation with different hydration levels, and their contribution to the changes in dough modulus.