» Does Yeast Go Bad?How Long Does It Last?

Does Yeast Go Bad?How Long Does It Last?


Nothing will ruin your baking day faster than dead yeast. So, if you have some yeast that has been in storage longer than recommended, you may want to find out if it’s still potent. But don’t worry. This post details everything you need to know about yeast’s shelf life, including tips to find out if that packet you have on hand still got its leavening superpower. Let’s jump right in!

Does Yeast Go Bad?

Yes, yeast does indeed go bad. However, its shelf life depends on whether the product is dry or fresh, with dry yeast retaining its potency much longer than its fresh counterpart.

The difference between dry and fresh yeast is that the former comes in dehydrated granules while the latter comes in form of blocks. Which one you choose boils down to personal preference, but fresh yeast has been found to produce better baked foods, and it’s sometimes even referred to as the baker’s yeast.

Both yeast types usually have a best-by date printed on the package. However, the product will not go bad immediately after this date but after some time, it will lose its leavening power and won’t be as productive. Fresh yeast will lose its potency in just a few days after this date while dry yeast will stay fresh a little longer.

How Long Does Yeast Last?

The answer to this question, as stated, will depend on the type of yeast you have. Dry yeast has a much longer shelf life than fresh yeast, with most brands giving a best-by date of between one and two years.

But as we mentioned, this doesn’t indicate that the product will immediately start to produce flat baked goods; it only marks when it starts to deteriorate. If a packet of yeast is left unopened, it can be used for an extra two to four months beyond the indicated period.

After the packet is opened, the leftover yeast should be sealed properly and stored in the refrigerator. Here, it will stay good for about two to three months, and up to six months if frozen.

Fresh yeast, on the other hand, stays potent for only three weeks to a month after production and only seven days after the best-by date. Some techniques for storing fresh yeast like freezing, however, can help you enjoy the product much longer, sometimes up to five months.

Of course, these are not hard and fast rules. If you are not following proper storage practices, the product will degrade much faster.

The following table better explains the shelf life of both dry and fresh yeast in different storage conditions.


Yeast Type

Pantry Refrigerator Freezer
Unopened dry yeast Best-by date + 2 to 4 months N/A N/A
Opened dry yeast Not recommended 2 to 3 months Up to 6 months
Fresh yeast (opened or unopened) Not recommended Best-by date + 7 days max Up to 5 months

2 Tips to Tell if Yeast Has Gone Bad

If your yeast has been in storage beyond the recommended time, there are some tricks you can use to find out if the product is still good to use. Here are the two most effective ones:

1.    Performing a Potency Test

Also known as proofing, performing an actual test to check for your yeast potency is by far the most effective way to know if the product can still produce the desired results. The process works both for dry and fresh yeast. Here are the steps to follow:

  1. Mix a teaspoon of sugar with ¼ cup of warm water in a bowl. Use a kitchen thermometer to ensure the water temperature ranges between 100° and 115° F, which is the ideal temperature for yeast to activate. Do not use hot water; if the temperature is higher than 140° F, you will ruin the yeast.
  2. Add 2 teaspoons of dry yeast to the mixture. If you are testing fresh yeast, cut a small slice of the yeast and dip it into the solution.
  3. Stir the mixture completely, then let sit for about 5 to 10 minutes in a warm area. This is the amount of time yeast usually takes to activate. If the solution is placed in a colder spot, you may want to give it a little more time.
  4. When the yeast is activated, it will foam up to almost twice the height of the solution. If it doesn’t produce any foam, then that’s a sign it has lost its potency and will likely produce flat foods. Get fresh yeast.

For a step-by-step guide on how to test for yeast potency, watch this video:

2.    Using Your Senses

Your sense of sight and smell can come in handy when you want to know if your yeast is spoiled. Start by carefully looking at the yeast. If you see a change in color, that product is probably done for.

For fresh yeast, check for dryness too. If there are cracks on the outside, that’s an indication that the product has lost its moisture and there is no point in using it because it has probably lost its potency too. But you may want to perform a proofing test just to be sure.

If the yeast looks okay but you are still questioning its integrity, sniff it. Good yeast should smell earthy and yeasty. If it gives off an unpleasant odor, it has likely gone bad and you should discard it.

Fresh yeast that has developed mold can emit a moldy smell too. Check to see the extent of the damage. If the mold covers only a small area, just chop off the affected area and proof the rest to see if it is still potent.

3 Tips to Store Yeast

How you store your yeast will vary based on whether you are dealing with dry or fresh yeast. Here are some tips to guide you.

1.    Store Opened Dry Yeast in the Freezer

Dry yeast is shelf-stable, thus an unopened packet will be just fine at room temperature. However, as soon as the seal is broken, the product will start to deteriorate and if it’s not stored properly, it can lose its leavening power pretty fast.

That said, the best place to store an opened packet of dry yeast will be the refrigerator. The cold temperatures will prevent the product from going bad quickly, allowing it to serve you longer. A much better option would be to freeze it, with frozen yeast lasting up to six months.

2.    Keep Fresh Yeast in the Refrigerator

Fresh yeast belongs in the fridge, and that’s why it is stored in the refrigerated section of the grocery store. If you hope to enjoy it for an extended time, let it sit in the fridge, or even better, freeze it.

3.    Seal Yeast Tightly Before Storage

It doesn’t matter the type of yeast you have or where you store it; always make sure it is tightly sealed before you put it away. Sealing keeps dry yeast from absorbing moisture from the atmosphere and fresh yeast from drying up, all of which is important in retaining the product’s potency.

The Risk of Consuming Expired Yeast

Ingesting expired yeast will basically not harm you. This is because, contrary to what many people think, the date printed on the label doesn’t indicate the expiration of the product. It only states when the product will start deteriorating and perhaps losing its leavening power.

As such, the worst that can happen is that the baked goods will not rise but you will not get sick from ingesting foods made from the yeast.

However, things may be different if the yeast is moldy or has an awful smell or taste. Such yeast could actually be unsafe to eat, so much so, that it may cause food poisoning that could result in an array of digestive disorders. If you experience diarrhea, nausea, vomiting, heartburn, or stomach pain that lasts for more than two days, have it checked by a doctor.

Can You Freeze Yeast?

Yes, freezing gives your yeast a much longer shelf life. While unopened dry yeast will not require freezing, as soon as the packet is opened, that yeast will need refrigerating, but it will last much longer if stored in the freezer. Simply seal the product tightly, put it in an airtight container or Ziplock bag and place it in the freezer.

Similarly, fresh yeast will retain its quality better in the freezer. The freezing process is pretty straightforward. All you need is to slice the giant block into smaller portions, wrap each piece in aluminum foil, and put the yeast in an airtight container or freezer bag. After that, chuck the yeast into the freezer for long-term storage.


Yeast, like all leavening agents, doesn’t last forever. But whether yours retains its quality up until the printed date and long after that will depend on how you store it. Dry yeast will keep good in the pantry but must be refrigerated as soon as the packet is opened and fresh yeast should be refrigerated at all times. These measures will keep your yeast from going bad prematurely.


  1. How Long Is Yeast Good for?
  2. How Long Does Yeast Last?
  3. How to Store Yeast
  4. How to Store Active Dry Yeast
  5. How Long Does Yeast Last? Guide To Active Dry, Instant, and Fresh Yeast

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