How to Proof Yeast

Hands up if you’ve made a loaf of yeasted bread that didn’t rise.

It happens, and it’s not fun. The culprit may have been the yeast. It doesn’t last forever, and proofing is a way to check that yeast is alive and ready to power up your bread.

What Does “Proof Yeast” Mean? 

Proofing yeast tests its vitality—you’re proving it’s vigorous enough to make dough rise.

To proof yeast, you dissolve the yeast in warm water with sugar and wait until it’s creamy-looking with many small bubbles, which indicate the yeast cells are doing their thing.  

What Kinds of Yeast Need to Be Proofed? 

The only yeast that requires proofing is yeast you suspect is old.

Surprised? Welcome to the new world of commercial yeast.

In the somewhat recent past, only one kind of yeast – active dry yeast – required proofing. But manufacturers have re-formulated active dry yeast so proofing is not required. You can now just add it straight to dough!

In fact, things have changed so much in the world of commercial yeast that, technically, no yeasts require proofing anymore. Active dry, instant, bread machine, rapid rise, and fresh cake yeast – most times they will not need to be proofed, unless you suspect they might be old.

There are two possible exceptions:

1.   Cake yeast: Fresh cake yeast is highly perishable, and retail stores don’t have a high turnover. For home bakers wanting to avoid dense loaves, proofing cake yeast is still a good idea.

2.   Instant yeast in a dough with a hydration of 70% of less: In hand-kneaded stiff doughs with little moisture (hydration of 70% or less), it helps to pre-dissolve instant yeast before adding it to the dough to help distribute the yeast better. Pre-dissolving (proofing without sugar) might not be necessary in such doughs if you are using an electric stand mixer.

How to Proof Any Dry Yeast

If you suspect your yeast might be a bit old and you want to proof it to check, here's how to do it.

1. Warm the water:

   Measure the water called for in your recipe, and then warm it to 110° to 115°F (nice and warm, but not hot).

2. Add sugar:

   Add a fat pinch of sugar to feed the yeast.

3. Add yeast and rest:

   Mix in the yeast. Set it aside.

4. Wait 5-10 minutes, then look for foamy bubbles:

   In 5-10 minutes, you should see lots of small bubbles. Proceed with the recipe. If you don’t see foamy bubbles, the yeast is past its prime. Time to start with new yeast! Once yeast is proofed, don’t let it sit around, or it’ll lose its vitality.

How to Proof Fresh Cake Yeast

1. Dissolve some sugar in warm water:

   Dissolve 1 teaspoon of sugar in 1/2 cup of moderately warm liquid (90° to 95°F).

2. Crumble cake yeast in water and let dissolve:

   Crumble the yeast into the water and stir until it’s dissolved.

3. Let it stand, then look for foaming:

   Let it stand until you see plentiful foaming, about 5 – 10 minutes. If it’s not nice and bubbly after 10 minutes, throw it out and try with new yeast.