How long does yeast last? (+3 steps to test)

In this article, we will answer the question “How long does yeast last?”, and how to tell If the yeast is still active?

How long does yeast last?

The following table shows an approximate time during which the yeast may still be active past the expiry or the best before date. If you are unsure whether to use or discard your yeast, it is recommended to perform the yeast freshness test.

In the refrigeratorIn the freezer
Past printed datePast printed date
Dry active yeast(unopened)2-4 months4 months
Cake yeast(unopened)1-2 weeks2-3 months
Dry active yeast(opened)4-6 months6 months
Cake yeast(opened)4 monthsNot recommended

How to tell if yeast is active?

You cannot tell by looking at the yeast if it is dead or not. Perform the test below to check if the yeast is active.

  1. In a cup, take ¼ cup lukewarm water. It is best to check the temperature of the water using a thermometer and make sure it lies between 110-115°F. A temperature higher than 120°F will destroy your yeast. A temperature lower than 110°F will not be able to activate the yeast to its full potential. To the water, add 1 ¼ tsp of yeast and 1 tsp of granulated sugar.
  2. Give it a stir until yeast is dissolved completely. Wait for 10-15 minutes.
  3. If the yeast forms bubbles or foam on the surface and you smell a strong yeasty aroma, the yeast is active. If not, the yeast is dead.

This proofing test can also be performed with a small amount(walnut-sized) dough. 

How to tell if yeast is active?

You cannot tell by looking at the yeast if it is dead or not. Perform the test below to check if the yeast is active.

  1. In a cup, take ¼ cup lukewarm water. It is best to check the temperature of the water using a thermometer and make sure it lies between 110-115°F. A temperature higher than 120°F will destroy your yeast. A temperature lower than 110°F will not be able to activate the yeast to its full potential. To the water, add 1 ¼ tsp of yeast and 1 tsp of granulated sugar.
  2. Give it a stir until yeast is dissolved completely. Wait for 10-15 minutes.
  3. If the yeast forms bubbles or foam on the surface and you smell a strong yeasty aroma, the yeast is active. If not, the yeast is dead.

This proofing test can also be performed with a small amount(walnut-sized) dough. 

Can I use expired yeast?

You can use expired yeast but it may not be as potent as fresh yeast. Yeast packets have a best before date rather than an expiration date. After the expiry, yeast can be used from 1 week to as long as 6 months. 

Yeast is a fungus that is used to ferment your dough. During fermentation, yeast produces carbon-di-oxide gas that leavens your dough when it gets trapped in the crumb structure.

When the yeast is dead, it cannot ferment your dough.

Different types of Yeast used in baking

Instant yeast

It has a smaller grain size and a greater number of live yeast cells per unit volume than active dry yeast. As the name suggests, this yeast needs no time for rehydration and is directly poured into the dough mixture.

Osmotolerant yeast

High salt and sugar concentration hinder yeast growth. Hence, in bread with higher sugar content, osmotolerant yeast comes to the rescue.

Cream yeast

Cream yeast is just compressed yeast in a liquid state. This compressed yeat slurry is widely used by bread industries.

Active dry yeast

It is relatively stable than other forms of yeast and has bigger grains than instant yeast. It is sold in its dormant form and requires proofing before adding to the dough.

Brewer’s yeast

As the name suggests, it is used by breweries to make alcohol. Brewer’s yeast is also used for its nutritional benefits. It keeps the digestive system healthy and has considerable amounts of chromium.

Rapid-rise yeast

It is a type of instant yeast but with smaller grain size and a greater dissolution rate. It provides a pronounced carbon-dioxide yield.

Compressed yeast

It is basically dry cream yeast shaped into small or large blocks wrapped with foil. Despite being very perishable, it is still used in bakeries.

Conclusion

In this article, we answered the question “How long does yeast last?”, and how to tell If the yeast is still active?

References

https://www.thespruceeats.com/how-long-is-yeast-good-for-1388307

https://www.doesitgobad.com/does-yeast-go-bad/

https://www.thespruceeats.com/how-long-is-yeast-good-for-1388307

https://www.doesitgobad.com/does-yeast-go-bad/#:~:text=Dry%20yeast%20usually%20comes%20with,yeast%20it’s%20not%20a%20given.&text=Once%20you%20open%20the%20package,6%20months%20in%20the%20freezer

Sana Ameer

Hello, I'm Sana Ameer. I'm a student of Food Science and Technology at UVAS. I like to bake and I aspire to become a Food blogger.

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