Yeast is a very useful product for many food and beverage industries.
Fresh yeast can only survive for one week at a controlled temperature of 4°C. Active dry yeast, however, can be maintained for three years, without any loss of properties.
Dry yeast is a compressed fresh yeast that has been pressed and dried until the moisture content is only 8%, which makes the yeast inactive. The granules are activated again only when mixed with a warm liquid. The advantage of dry yeast is that it has a much longer shelf life than fresh yeast and does not need to be refrigerated.