A novel approach for improving yeast viability and baking quality of frozen dough by adding biogenic ice nucleators from Erwinia herbicola

Freezing deteriorates the baking quality of frozen bread dough by causing lethal injury to yeast cells and depolymerization to the gluten network. To investigate the potential of biogenic ice nucleators in frozen food applications, the effect of extracellular ice nucleators (ECINs) from Erwinia herbicola on the baking quality of frozen dough upon three freeze/thaw cycles were investigated. With addition of ECINs to the activity of 2.4 × 106 units per gram of dough, hardening of bread crumb caused by three freeze/thaw cycles was alleviated by about 50% compared to the control. Additionally, the bread from frozen dough with added ECINs showed 50% larger specific volume compared to the control. The mechanism of cryoprotective effects from ECINs was possibly that ECINs helped in preserving the viability of yeast cells during freeze/thaw cycles. ECINs were able to improve the viability of log-phase and stationary-phase yeast cells in suspensions by about 100 and 10 fold, respectively, and viability of yeast in the frozen dough by 17%. This study revealed the potential of ECINs as a cryoprotectant for applications in the food and biotechnology industries.