Yeast, given by a microorganism that consumes sugars to produce carbon dioxide and alcohol, is an essential component of many baked and fermented products. By "reviving" or "refreshing" we mean the procedure by which you check if the yeast is still active and make it act faster. Modern yeast packaging techniques make this process less necessary, but it is always best to revive a yeast that has been kept in the pantry for a long time.
Steps
Method 1 of 2: Revive the dry yeast
Step 1. If you are using instant yeast, skip this method entirely
Instant or fast leavening yeast do not need to be revived, and can be added directly to dry ingredients. This yeast is always active and has a long shelf life. Some pastry chefs think these types of yeast taste worse than fresh yeast, but others don't feel the difference.
Never use brewer's, champagne or wine yeast for baked goods.
Step 2. Measure a small amount of water or milk
Put the water or milk in a heat-resistant container, and write down the amount. No matter how much you add, the important thing is to subtract this amount from the total liquid needed for the recipe. 120ml should be more than enough for the common bread recipe.
For example, if you are using 120ml of water to revive the yeast and the recipe calls for 240ml of water in all, remember to add only 120ml on top of the water already used for the yeast
Step 3. Warm the liquid
Warm the liquid to 40–43ºC, a warm but not hot or steaming temperature. Although yeast works best at slightly lower temperatures, active dry yeast needs a little more heat to start working.
If you don't have a food thermometer, heat the liquid slightly, taking care not to overdo it. A warmer liquid will take longer to activate the yeast, but too hot a liquid will kill the leavening agent or the yeast will not work at all
Step 4. Add a teaspoon (5ml) of sugar
To revive the yeast you only need warm water, but the sugar is used to check if the yeast is ready. The active yeast will consume the sugar and form carbon dioxide and other substances, and this is the process that causes the bread dough to rise and give it its distinctive flavor. Quickly mix the sugar to dissolve it.
If you forgot to add sugar to the liquid, you can add it after you have already put the yeast in the water. The effect will be the same, but you will need to mix slowly to avoid spilling the yeast from the container or spoiling it
Step 5. Spread the yeast on the liquid
Take the amount of yeast required by the recipe and sprinkle it on the liquid. If the recipe called for fresh yeast, using dry yeast instead you have to halve the quantity, because dry yeast is more concentrated. If the recipe calls for instant yeast use 1.25 times as much dry yeast.
Be aware that some types of yeast expand when you add them to the water. If necessary, change the container to avoid spills
Step 6. Stir the yeast after 30–90 seconds
As the yeast sits on the surface of the water or sinks slowly, the water will dissolve the inactive coating and release the active interior. After the time necessary for this to happen, gently mix the yeast with the water.
It is not necessary to time perfectly. Even if you mix it right away, the yeast will not be damaged
Step 7. Wait ten minutes and watch for bubbles or foam
If the yeast is alive and active it will begin to consume sugar and produce carbon dioxide, the gas that causes bread to rise. If you see foam or bubbles on the surface it means that the yeast is active and can be added to the other ingredients.
- You may need to look closely at the rim of the bowl to see the bubbles.
- Other signs of activity can be a distinct "yeasty" smell and an increase in volume, but they are not always noticeable.
- Unfortunately, if the mixture does not foam, the yeast is probably inactive and cannot be used. You could add a little warmer water, no more than 43ºC, and let it sit for another 10 minutes. If it still doesn't foam, throw it away.
Step 8. Add this blend when the recipe says so
Don't try to filter the yeast.
Method 2 of 2: Revive the fresh yeast
Step 1. Examine fresh yeast for problems
Fresh yeast refers to yeast packaged in slightly moist loaves, which remains active but does not last as long as dry yeast. Keep in mind that fresh yeast shouldn't freeze, it lasts one to two weeks at room temperature and one to three months in the fridge at the most. If it has hardened or turned dark brown, it is probably not usable. You can still revive it to see if it works, but it's best to have more yeast on hand so you don't have to interrupt to go and buy it.
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Note:
fresh yeast is also known as cake or dough yeast.
- Do not never confuse brewer's yeast with fresh baker's yeast. Use only the latter when making cakes or bread.
Step 2. Put a small amount of water or milk in a heat resistant container
Take 60ml of the required amount of liquid for the recipe. You can use more if you need a lot of yeast, but be sure to write down the amount you used to subtract it from the total amount.
For example, if the recipe calls for 240ml of milk and you use 60ml to revive the yeast, then you will only need to add 180ml
Step 3. Heat the liquid
Heat the liquid slightly, between 27 and 32ºC, a temperature that favors the maximum activity of the yeast. The fresh yeast is already active, so it is not necessary to heat more than the liquid.
- This temperature is lukewarm. If, on the other hand, you see steam or a thin film forming on the surface, it means that the milk is too hot and can kill the yeast.
- Since fresh yeast contains moisture, in theory you shouldn't need to add water. It is recommended to add water as the temperature in the room may not be high enough to revive the yeast. If the room is already warm you can simply mix the yeast and sugar.
Step 4. Add a teaspoon (5ml) of sugar
Yeast feeds on almost any type of sugar, so you can use refined, raw, or anything natural and sweet. Artificial sweeteners cannot be used for any type of yeast.
Step 5. Add the yeast to the liquid
Gently mix the amount of fresh yeast called for in the recipe. Since fresh yeast contains liquids, you will need to adjust the amount if the recipe mentions another type of yeast:
- If the recipe uses active dry yeast you have to use twice as much fresh yeast (for example, for 5 g of dry yeast you need to put 10 g of fresh yeast).
- If the recipe uses instant yeast use 2.5 times the amount of fresh yeast.
Step 6. Wait a few minutes for bubbles to form
If foam or bubbles form within 5 or 10 minutes the yeast is active and usable, otherwise, unless the liquid is too hot or cold, the yeast is probably unusable and to be thrown away.
Since fresh yeast remains active, it should take less time to revive than dry yeast
Advice
- If you are making a dough you can revive the yeast in the same container you put the dry ingredients in. Make a hole in the flour and use it as if it were a bowl.
- As for sugar, almost anything that contains chemical sugar (sucrose, fructose, etc.) and has little or no acid is fine: raw, refined sugar, molasses, fruit juice. Artificial sweeteners don't work.
- A smell similar to beer or bread is normal as the yeast revives.
- If you don't have much time and the yeast you have around the house hasn't been bought recently, you may want to give it a try before you start baking. If the yeast is not active you can go and buy more.
- Light can destroy yeast, which is why bread dough recipes say to keep it in a covered bowl.
Warnings
- Do not add yeast to cold or hot water. Temperatures below 10ºC will not activate the yeast, and temperatures above 50ºC will kill the leavening agent.
- Salt can slow down the action of the yeast, and if it is too much it can kill the leavening agent. Add the salt to the other dry ingredients, not the bowl with the yeast, even if the recipe says otherwise.
