Thermal-aggregation behavior of gluten in frozen dough induced by ε-poly-L-lysine treated yeast

ε-poly-L-lysine treated yeast (PTY) helps to enhance the freeze-thaw tolerance of frozen dough. This study explored the effect of PTY on the aggregation and the gas-retention of frozen dough after steaming for 2, 5, 10, and 20 min. Gas-cell images showed that PTY reduced the loss of gas-retention ability caused by 4 times of freeze-thaw. The results of sodium dodecyl sulfate extractability and subunit distribution of gluten showed that, after the same heat time, frozen dough with PTY has higher degree of covalent crosslinking with better aggregation ability of α-, γ-gliadin, and low molecular weight glutenin subunits than frozen dough with yeast. Chemical analysis and chain morphology results demonstrated that the levels of acidity, NH₂, and free sulfhydryl in dough were decreased, and the protein molecules aggregated into longer chains when using PTY instead of yeast, indicating that PTY reduced acid-mediated hydrolysis and increased the disulfide bonds-mediated gluten polymerization.