What Temperature Kills Yeast

, a microorganism commonly used in bread making and , is highly sensitive to temperature. Different types of yeast have varying temperature ranges in which they thrive and can effectively carry out fermentation. Understanding the temperature limits of yeast is crucial for successful baking and brewing processes.

Yeast generally prefers temperatures between 21'C and 54'C (70'F and 130'F), depending on the specific type of yeast. However, for most bakery applications, the temperature range of 32'C to 43'C (90'F to 110'F) is commonly used. These temperatures provide an ideal environment for yeast to flourish and produce the desired fermentation.

At lower temperatures, particularly below 2'C (34'F), yeast becomes dormant. This decrease in temperature slows down its metabolic activity. Therefore, when it comes to storing fresh yeast, it is recommended to keep yeast bread ideally between +2 and +4°C to maintain its viability and prolong its shelf life.

On the other hand, excessively high temperatures are detrimental to yeast survival. When yeast is exposed to temperatures above 59'C (138'F), it dies. The heat denatures the proteins within the yeast cells, rendering them unable to carry out their essential functions. Consequently, yeast that has been subjected to such high temperatures becomes nonviable and cannot be used for fermentation.

It is important to note that different types of yeast may have slightly different temperature tolerances. For instance, yeast, known scientifically as Saccharomyces cerevisiae, can ferment within a range of 60 to 80 degrees Fahrenheit. However, as temperatures exceed 100 degrees Fahrenheit, the yeast cells begin to die off, leading to a decrease in fermentation activity.

When working with yeast, it is crucial to ensure that the temperature is within the appropriate range for the specific yeast strain being used. Using yeast outside its recommended temperature range can result in poor fermentation, leading to less desirable outcomes in baking and brewing.

To determine if yeast is still viable, it is essential to observe its reaction in a warm liquid. When yeast is added to warm or milk with a small amount of sugar, it should begin to bubble, foam, and show signs of activity within a few minutes. This reaction indicates that the yeast is alive and ready for use. If there is no reaction or if the yeast is reacting very slowly, it is best to discard it and purchase fresh yeast to ensure optimal fermentation.

Yeast is highly sensitive to temperature. It thrives within a specific temperature range, with temperatures above and below this range being detrimental to its viability and fermentation capabilities. Understanding the temperature limits of yeast is crucial for successful baking and brewing endeavors. By maintaining the appropriate temperature range, one can ensure the yeast's optimal performance and achieve desired results in their culinary creations.

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What Temperature Does Yeast Go Dormant?

Yeast goes dormant at temperatures below 2'C (34'F). It becomes inactive and stops its metabolic activity at this low temperature range. Below this point, the yeast is essentially in a state of hibernation and will not be able to carry out its normal functions.

It is important to note that yeast is a living organism and its activity is highly dependent on temperature. Cold temperatures significantly slow down the yeast's metabolism, leading to dormancy. This is why yeast is often stored in refrigerators or cool environments to keep it dormant until it is ready to be used.

To summarize, yeast goes dormant when exposed to temperatures below 2'C (34'F). This temperature range halts its activity and puts it in a state of hibernation.

What Is The Lowest Temperature Yeast Will Work?

The lowest temperature at which yeast will work is around 2°C to 4°C. At temperatures below 10°C, the metabolism of the yeast cell slows down. This means that the yeast's ability to ferment and produce carbon dioxide, which is essential for the rising of bread dough, is greatly reduced.

To ensure the optimal storage and performance of fresh yeast, it is recommended to keep it at a temperature between 2°C and 4°C. This temperature range helps to maintain the yeast's activity while slowing down its metabolism, which in turn prolongs the yeast's shelf life.

The lowest temperature at which yeast will work is between 2°C and 4°C. Below this temperature, the yeast's metabolism slows down, affecting its ability to ferment and produce carbon dioxide for bread dough rising. Storing fresh yeast within this recommended temperature range helps maintain its activity and extends its shelf life.


Yeast is a delicate organism that is highly sensitive to temperature. Its preferred temperature range for optimal growth and fermentation is between 21°C and 54°C (70°F and 130°F). Most bakeries use a temperature range of 32°C to 43°C (90°F to 110°F) for yeast activation and bread fermentation.

At temperatures below 2°C (34°F), yeast becomes dormant, slowing down its metabolic activity. This is why it is recommended to store fresh yeast between 2°C and 4°C for longer shelf life. However, if yeast is exposed to extremely cold temperatures, below freezing point, it can become damaged or die off.

On the other hand, temperatures above 59°C (138°F) are lethal for yeast. At these high temperatures, the yeast cells cannot survive and will be completely killed off. This is why it is crucial to avoid exposing yeast to excessive heat during the baking process.

It is important to note that using expired or partially expired yeast can also lead to poor results in bread making. If the yeast does not show any signs of activity such as bubbling, foaming, or reacting, it is likely dead and should be discarded. Using inactive or partially expired yeast can result in problem loaves and may not produce the desired rise and flavor.

Maintaining the proper temperature range is crucial for yeast activation, fermentation, and successful bread baking. Too cold or too hot temperatures can have detrimental effects on yeast, either slowing down its activity or killing it off completely. To ensure the best results, it is recommended to follow the recommended temperature guidelines for yeast storage and usage.

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Thomas Ashford

Thomas Ashford is a highly educated brewer with years of experience in the industry. He has a Bachelor Degree in Chemistry and a Master Degree in Brewing Science. He is also BJCP Certified Beer Judge. Tom has worked hard to become one of the most experienced brewers in the industry. He has experience monitoring brewhouse and cellaring operations, coordinating brewhouse projects, and optimizing brewery operations for maximum efficiency. He is also familiar mixology and an experienced sommelier. Tom is an expert organizer of beer festivals, wine tastings, and brewery tours.