As a sommelier and brewer, I have had the opportunity to work with yeast in various fermentation processes. When it comes to the temperature at which yeast dies, there is a general rule that yeasts will start to die off between 105 and 108 degrees Fahrenheit (40-42 degrees Celsius). However, it's important to note that this temperature range can vary depending on the specific strain of yeast and the conditions in which it is fermenting.
In the case of wine fermentation, as the alcohol content increases, the terminal temperature at which yeasts can survive actually decreases. This means that as a wine approaches around 10% alcohol content, the temperature at which the yeast will die off can be as low as 90 degrees Fahrenheit (32 degrees Celsius).
This lowering of the terminal temperature is a result of the presence of alcohol in the fermentation environment. Alcohol is toxic to yeast, and as it accumulates in the wine, it creates a more hostile environment for the yeast cells. This, in turn, lowers the temperature threshold at which the yeast can survive.
It's worth mentioning that different strains of yeast have different tolerances to temperature and alcohol. Some yeast strains are more heat-tolerant and can withstand higher temperatures, while others are more sensitive and will die off at lower temperatures. As a brewer, it's important to select the appropriate yeast strain for the specific fermentation process to ensure optimal results.
In my own brewing experiences, I have encountered situations where the temperature of the fermentation got too high, causing the yeast to die off prematurely. This can lead to off-flavors and incomplete fermentation. It's crucial to carefully monitor and control the temperature during fermentation to create the ideal conditions for yeast activity.
The temperature at which yeast dies off can vary depending on the specific strain and the presence of alcohol. As a general guideline, yeasts will start to die off between 105 and 108 degrees Fahrenheit, but as the alcohol content increases, this terminal temperature can lower to around 90 degrees Fahrenheit. It's important for brewers and winemakers to monitor and control the fermentation temperature to ensure the yeast can thrive and complete the fermentation process successfully.