How hot is too hot for yeast?

In this brief guide, we are going to answer the question “how hot is too hot for yeast” with an in-depth analysis of the temperature at which yeast begins to die. Moreover, we are going to discuss other factors that can potentially kill the yeast.

So without much ado, let’s dive in and figure out more about it. 

How hot is too hot for yeast?

The temperature of 120 degrees Fahrenheit or higher is too hot for the yeast. Yeast is temperature sensitive and when the temperature of the water that you are adding in the yeast increases by 120 degrees Fahrenheit the yeast begins to degrade. 

If the temperature of the water reaches 140 degrees Fahrenheit or above, the yeast present in the solution fully gets killed. This means that if your hot water has a temperature of more than 120 degrees Fahrenheit then it can kill your yeast. 

Therefore care should be taken in this regard or else you will be left with dead yeast that won’t be able to carry out any function. 

It is worth mentioning that if we compare instant yeast with active dry yeast, we can see that they have different tolerable temperature limits, with instant dry yeast tolerating hotter water than active dry yeast.

For example, if the temperature rises beyond 115 degrees Fahrenheit, the active dry yeast will deteriorate and cease to function. The quick-dry yeast, on the other hand, can withstand temperatures of up to 130 degrees Fahrenheit.

So all in all, the yeast dies at a temperature of around 120 to 140 degrees Fahrenheit. If your water reaches 120 degrees Fahrenheit or higher, the yeast will begin to die off, regardless of the type of yeast you use. 

When the temperature of the water reaches 140 degrees Fahrenheit or above, the yeast is entirely killed, and when the yeast is killed, it can no longer perform its leavening function, regardless of which dough or batter it is added to.

The optimum temperature for activating the yeast

Yeast needs warm temperatures to be activated, so while putting the dough to rise, make sure that it is sitting at a temperature that is 70 to 80 degrees Fahrenheit, so that yeast can work optimally.

Other factors that can potentially kill the yeast

There are a  couple of factors including the addition of salt or sugar that can potentially kill the yeast.

Salt

Salt slows the activity of yeast because it slows down the rate at which it performs its function. However, if a large amount of salt is added to a yeast-containing dough, the yeast could be killed.

As a result, if you oversalt the dough, expect a flat and cakey bread loaf, as the yeast will have perished and won’t be able to complete the fermentation process that would otherwise result in the bread or dough leavening.

One of the reasons that can be the potential cause of why salt kills yeast can be that salt is hygroscopic. So when it comes in contact with the yeast, it draws out water from the body of the yeast, thereby induces osmotic stress on the yeast and ultimately kills it.

Sugar

There are also some claims that the addition of too much sugar can also harm the yeast and can even kill it and the reason behind these claims is again the hygroscopic nature. So when it comes in contact with the yeast, it draws out water from the body of the yeast, thereby induces osmotic stress on the yeast and ultimately kills it.

You can read the behavior of yeast at different temperature ranges here.

Tips to keep yeast fresh for a long time

  1. In the case of the unopened dry yeast, you should store it in a cool, dry, and dark corner of your pantry or kitchen cabinet away from direct sunlight and heat.
  1. Once you have opened the package of the active yeast it is best to store it in a plastic zipper bag or an air-tight container so that no moisture will find its way to the yeast.
  1. It is worth mentioning that the sunlight, oxygen, and moisture can degrade the quality of the active yeast and can also shorten its shelf life therefore care should be taken while handling and storing active yeast.
  1. You should never store yeast in a humid environment.
  1. You should always store the opened yeast in an air-tight container or plastic zipper bag at or below 40 degrees centigrade in the refrigerator.
  1. You should not use a wet spoon to scoop out the dry yeast.
  1. Close the lid of the jar as soon as you scoop out the dry yeast so that the moisture won’t find its way into your yeast and spoil it.
  1. In the case of fresh yeast, it is recommended to refrigerate the unopened as well as opened fresh yeast.

Conclusion

In this brief guide, we answered the question “how hot is too hot for yeast” with an in-depth analysis of the temperature at which yeast begins to die. Moreover, we discussed other factors that can potentially kill the yeast.

Citations

https://www.cooksillustrated.com/how_tos/8363-the-impact-of-too-hot-water-on-yeast
https://findanyanswer.com/what-temperature-is-too-hot-for-yeast
https://food52.com/blog/12880-get-the-right-water-temperature-for-yeast-without-a-thermometer

Mahnoor Asghar is a Clinical Nutritionist with a bachelor's degree in Nutrition and Dietetics. She is compassionate and dedicated to playing her part in the well-being of the masses. She wants to play a fruitful role in creating nutrition and health-related awareness among the general public. Additionally, she has a keen eye for detail and loves to create content related to food, nutrition, health, and wellness.