Influence of ε-poly-l-lysine treated yeast on gluten polymerization and freeze–thaw tolerance of frozen dough

• Treating yeast with ε-poly- l -lysine decreased release of glutathione and reduced depolymerization of gluten. • The treatment protected integrity of the gluten network and quality of steamed bread made from frozen dough. • ε-Poly- l -lysine by itself affected dough properties less than yeast treated with it. The effects of ε-poly- l -lysine (ε-PL) treated yeast on gluten polymerization of frozen dough and quality of steamed bread after freeze–thaw cycles were investigated. Compared with steamed bread made from frozen dough containing ε-PL and untreated yeast (PUTY) or only untreated yeast, steamed bread made from frozen dough containing ε-PL treated yeast (PTY) had a larger specific volume, lower hardness and more porous. A dynamic rheological and scanning electron microscopic analysis demonstrated that using PTY instead of yeast could reduce dough elasticity and damage protein network after freeze–thaw cycles. Lower sodium dodecyl sulfate (SDS) soluble polymeric proteins and monomeric proteins, and higher SDS insoluble proteins were found in frozen dough containing PTY, which indicates a reduced depolymerization of gluten proteins after freeze–thaw cycles. After 4 freeze–thaw cycles, the lower glutathione and free sulfhydryl in dough containing PTY indicate that the interchain disulfide bonds between proteins were preserved.