Testing Active Dry Yeast

The other day, I came across a recipe calling for active dry yeast. Although I usually just convert the yeast using my yeast converter, I happened to have some active dry yeast in the fridge, so I decided to use it. Since it had been sitting in the fridge for a while, I thought I’d better test it to make sure it was still viable. It’s easy to test active dry yeast, and if you have any doubts if it is still alive, you should take a few minutes to make sure.

To test the yeast, measure 1/4 cup warm water in a one-cup measuring cup. Stir in 1/2 teaspoon sugar; stir until it dissolves. Then stir in 1/2 teaspoon active dry yeast and stir to dissolve.

If your yeast is viable, you should see activity within three to four minutes. Within 10 minutes, the mixture should double and reach the 1/2-cup mark.

As you can see, this yeast failed the test and was discarded.



  1. Mary Witkowicz said,

    October 4, 2015 at 1:42 pm

    I was gifted a 1 lb bag of King Arthur dry instant yeast over 9 months ago. I still have about half of it, and it has been refrigerated in a glass jar. I decided to test it and it bloomed perfectly. Is there any reason to doubt its performance in baking? Is it unusual for yeast to survive so long? As money is tight, I do not want to discard a perfectly good product. Thank You

    • gaaarp said,

      October 6, 2015 at 8:09 pm

      I keep my instant yeast in the freezer, and it’s not unusual for a bag to last me more than 9 months. If it bloomed for you, it should be fine to bake with. Just make sure you let the dough rise to the correct stage according to the recipe. For example, if the recipe says to let it double during the bulk fermentation stage, don’t shape the dough until it has fully doubled, even if it takes longer than the suggested time.

  2. July 5, 2010 at 9:15 am

    […] as that’s what I keep on hand for baking. I had some active dry yeast in the fridge, but I tested some of it, and it was […]

  3. July 4, 2010 at 11:07 pm

    […] If you want to be sure your yeast is viable, check out this quick and easy yeast test. […]

  4. Frieda said,

    July 4, 2010 at 5:45 pm

    Better to give it a test run rather than run an entire batch bread! I was secretly hoping that your ADY would work so I could say, “It’s alive! It’s alive!” 🙂

    • gaaarp said,

      July 4, 2010 at 6:18 pm

      Actually, I was secretly happy that it was dead, so I could use my instant yeast for the Modern Baker recipes without feeling guilty for breaking the rules.

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