When I bake dim sum for my family, I often make too much dough and have to freeze it. Unfortunately, the dim sum made from the frozen dough never tastes as good as the ones from fresh dough.

A major reason for this problem is not the dough itself, but rather the baker’s yeast (Saccharomyces cerevisiae) that “lives” inside the dough and causes the dough to rise by producing carbon dioxide in a process called fermentation.

When we freeze the dough in a -20℃ freezer, we inevitably freeze and kill many of the yeast cells. So a good strategy towards this problem is to genetically manipulate, or modify, the yeast cells, making them to be more “freeze-tolerant”.

We identified a fast-fermentation yeast strain in our laboratory that also has enhanced freezing tolerance in frozen dough.

In our recent study published in Microbial Cell Factories, we identified a fast-fermentation yeast strain in our laboratory that also has enhanced freezing tolerance in frozen dough. It suggests that there exists a relationship between fast-fermentation and freezing tolerance.

In addition, we discovered that maltose metabolism and the content of cryoprotectant (trehalose) could be manipulated by sole maltase gene. We showed that such genetically modified yeast could significantly enhance freezing tolerance and increase the production of carbon dioxide, which is what makes the dough “fluffy”.

These findings are important to the baking industry that constantly seeks to improve the quality of fresh baked goods while meeting the demands of dough freezing for storage and transportation. It may also directly benefit the consumers. Someday, you may be able to purchase the freezing-tolerant yeast at a supermarket, and you will never need to worry about quality of the bread you make from the frozen dough.

And this is not the end of the story. The increased freeze-tolerance of microbes could be applied to other problems that involve microbial fermentation, such as the yogurt and cheese industry.