1, Yeast infection: Yeast infection is one of the most common causes of yeast graying. Infection usually occurs in a humid and warm environment, such as dough during fermentation or liquor during brewing. Infection can cause yeast to lose its vitality and turn gray or black.
2. Yeast death: Yeast will die under unfavorable environmental conditions, such as too high or too low temperature, too high or too low pH value, and lack of nutrition. When yeasts die, they turn gray.
3. Oxidation: When yeast is exposed to the air, it will undergo oxidation reaction, making its color turn gray. This usually happens when yeast is exposed to air for a long time or stored improperly.
4. Other factors: In addition to the above reasons, there are other factors that cause yeast to turn gray, such as bacterial infection, fungal infection and chemical pollution.