Yeast is a single cell microorganism. This tiny living creature has been used for baking and brewing through the fermentation process since ancient times. Without it, we might not discover the bread! Yeast is definitely important for us in making our food and we continue to use it even today.
It can be found everywhere, in the store. The most common yeast sold in-store is cells called Saccharomyces cerevisiae in a dry form. It looks like a powder, but it is a cell, living cells.
How they survive in a dry state remain a complex mysteries. Scientists believe they are actually able to stay in a dormant state when exposes to an extreme environment. It kind of similar to polar bear manage to survive without food for months in the extremely cold artic.
How yeast is produced
Yeast is produced in a culture broth by feeding them with the basic elements for living such as oxygen, carbon, and nitrogen. They rapidly multiply within hours and form a larger mass which is mostly a protein-based structure. After grown, the yeast is recovered by filtration. Then, the yeast is dried under controlled conditions to preserve their biological activities.
Dry yeast in the store consists of a minimum amount of water and could last for a few years at most. Fresh yeast always works better for baking, brewing, or any other fermentation process. Yeast can restart their biological activities if added into the water at 37 degrees Celcius.
Once the yeast is mixed well with dough and starchy crops, the fermentation process occurs. In this process, the yeast eats the starch and digest them to small sugars, alcohols, and carbon dioxide. Carbon dioxide releases from the process give soft and fluffy texture to the bread. If your bread is not fluffy probably because you use death yeast.