Content

• To step
• Method 1 of 2: Test active dry yeast
• Method 2 of 2: Test fresh yeast
• Tips
• Warnings

Yeast is a microorganism that uses sugars to produce carbon dioxide and alcohol - it is an essential part of many baked goods and beverages. In English we know the terms "Blooming" or "proofing", and the latter indicates what it is: a simple process to test if the yeast is alive and activate it quickly. Modern yeast packaging techniques have made this process less necessary, but testing yeast first is still a good idea for yeast that has been on the shelf for a long time.

To step

Method 1 of 2: Test active dry yeast

1. Skip this entire process if using instant yeast. Instant yeast or the "rapid-rise" yeast variety with smaller grains does not require testing and can be added directly to the dry ingredients. It is always active and has a long shelf life. Some professional bakers think that instant yeast and active dry yeast (more difficult to obtain in the Netherlands) produce a worse taste compared to fresh yeast, but others do not notice any difference in the end result.
   • Use never brewer's yeast, champagne yeast, or wine yeast for baking.
2. Measure out a small amount of water or milk. Pour a small amount of water or milk into a heatproof bowl and write down how much you use. The exact amount doesn't matter, but you do need to subtract this amount from the moisture in your recipe. 120 ml should be more than enough for a typical bread recipe.
   • For example, if you are using 120ml of water to test the yeast and the recipe calls for 240ml of water in total, use 120ml of water instead, as you will be mixing the remaining 120ml with the yeast.
3. Heat the moisture. Heat the mixture to 40-43ºC - that's warm but not hot or steaming. While yeast functions best at slightly colder temperatures, active dry yeast needs a little extra heat to start.
   • If you don't have a food thermometer, warm the liquid to a lukewarm temperature, aiming for a low temperature. With slightly cooler moisture it will take longer to activate the yeast, but it will be too hot and the yeast will die.
4. Dissolve a teaspoon (5 ml) of sugar. Only warm water is needed to activate the yeast, but sugar allows you to test whether the yeast is ready. Active yeast will eat the sugar and produce carbon dioxide and other substances, which is the very process that makes bread dough rise and give it a unique flavor. Stir in the sugar quickly until it is dissolved.
   • If you forget to add the sugar, you can add it after the yeast is already in the water. This is just as effective, but you need to stir more gently to avoid spilling or damaging the yeast.
5. Sprinkle the yeast over the liquid. Measure the amount of yeast required by the recipe and sprinkle it over the liquid. If the recipe calls for fresh yeast, use half that amount of active dry yeast, as dry yeast is more concentrated. If the recipe calls for instant yeast, use 1.25 times that amount of active dry yeast instead.
   • Note that some types of yeast expand when added to the water. Transfer to a larger container if necessary to avoid spillage during this process.
6. After 30 to 90 seconds, whisk the yeast into the water or milk. If the yeast is on the water surface or sinks slowly, the water will dissolve the inactive yeast layer and release the active yeast in the center. After taking the time to do this, gently stir the yeast into the water or milk.
   • There is no need to time this step exactly. The yeast is unlikely to be affected by the stirring, even if you stir it immediately.
7. Wait 10 minutes and watch for bubbles or foam. When the yeast is alive and active, it will begin to consume the sugar and release carbon dioxide (the gas that makes the bread rise).If the surface of the mixture becomes foamy or effervescent, the yeast is active and can be added to the other ingredients according to your recipe.
   • You may need to look for air bubbles around the rim of the bowl.
   • Other signs of activity may be a noticeable "yeasty" odor or increased volume, but these are not always noticeable.
   • Unfortunately, if the mixture does not foam, the yeast will likely be dead and cannot be used in recipes. You can add some heated water (no warmer than 43ºC) and let it sit for 10 minutes longer. If it still doesn't foam, throw it away.
8. Add the liquid yeast mixture if the recipe calls for yeast. When the recipe calls for the yeast to be added, add the liquid mixture with the yeast. Do not try to strain out the yeast.

Method 2 of 2: Test fresh yeast

1. Examine fresh yeast for potential problems. Fresh yeast is yeast that is stored in a slightly moist, packaged form, which keeps it active, but cannot be stored as long as modern dry yeast packs. Keep in mind that fresh yeast is unlikely to survive freezing and cannot be stored at room temperature for longer than 1-2 weeks, or refrigerated for up to 1-3 months. If the yeast has hardened or turned dark brown, it is probably not usable. You can still test it by making a paste to be sure, but it's a good idea to buy extra yeast in advance so you don't have to interrupt baking.
   • Note: fresh yeast is also called cake yeast, wet yeast or pressed yeast.
   • Use never liquid brewer's yeast instead of fresh baker's yeast. Only use baker's yeast (in any form) for baking.
2. Measure out a small amount of water or milk into a heat resistant container. Measure out 60 ml of liquid as directed in the recipe you plan to follow. You can use more if you need a lot of yeast, but make sure to write down how much you use so you can subtract this amount of moisture from the recipe.
   • For example, if a recipe calls for 1 cup of milk, and you are using 1 cup of milk to test the yeast, add only 1 cup of milk in addition to the yeast mixture.
3. Warm up the liquid. Heat the liquid slightly to 27 - 32ºC - that is the temperature that gives maximum yeast activity. Fresh yeast is already active, not dormant like some dry yeasts, so there is no need to heat the liquid further to "wake up the yeast."
   • This temperature is only slightly warm. Steam or a skin that forms on the milk means it is way too hot and can kill the yeast.
   • Since fresh yeast already contains moisture, you don't technically need additional water. Water is recommended in most cases as the room temperature may not be warm enough to activate the yeast. However, if the room is warm enough, you can just add sugar and yeast together.
4. Stir in a teaspoon (5 ml) of sugar. Yeast feeds on almost any type of sugar, so mix in a small amount of white sugar, brown sugar, or anything natural and sweet. Artificial sweeteners cannot be used to activate any type of yeast.
5. Add the yeast to the liquid. Gently stir the amount of fresh yeast into the liquid as per the recipe. Since fresh yeast contains some liquid ingredients as well as yeast, if the recipe calls for a different type of yeast, adjust the amount as indicated:
   • If the recipe calls for active dry yeast, use twice as much fresh yeast as the stated amount.
   • If the recipe calls for instant yeast, use 2.5 times the amount of fresh yeast.
6. Wait a few minutes and watch for air bubbles. If foam or bubbles form within 5 or 10 minutes, the yeast is alive and active and the mixture can be added if the recipe calls for yeast. Otherwise, assuming the liquid was neither too hot nor too cold, the yeast is likely dead and should be discarded.
   • Since fresh yeast remains active, its activation is unlikely to take as long as it does with dry yeast.

Tips

• When making a dough, you can activate the yeast in the same bowl in which you prepared your dry ingredients. Just make a well in the flour or meal and use it as if it were a regular bowl.
• If it is active, the yeast will likely give off a smell like beer or bread. This is normal.
• In terms of sugar, almost anything that contains natural sugars (such as sucrose, fructose, etc.) and has little or no acid can be used: brown sugar, white sugar, molasses or fruit juice can all work. Artificial sweeteners don't work.
• If you want to bake something quickly and the yeast you have was not recently purchased, you may want to test it in a bowl before you start baking. If the yeast doesn't work, you still have time to go to the store and buy another pack.
• Light can destroy yeast. That's why many bread recipes suggest keeping the dough in a covered bowl.

Warnings

• Do not add yeast to water that is ice cold or warm to the touch. It can kill the yeast, or at least won't activate it.
• Temperatures below 10ºC will cause the yeast to go dormant, and temperatures above 50ºC will kill it.
• Salt can slow down or even kill yeast activity in high concentrations. In the recipe, add salt to the other dry ingredients, not to the bowl of the yeast mixture, even if the recipe instructs otherwise.