The instant and active dry yeast you use for baking is actually a living microorganism (Saccharomyces cerevisiae). This organism is very sensitive and can die if kept in the wrong storage conditions.
Dead yeast won’t work so it’s important that you store yeast in a way that keeps it alive.
Shelf Life of Yeast
Fresh yeast has a very short shelf life of just about 3 weeks in the fridge. By contrast, active dry yeast and instant yeast are freeze-dried. Freeze-drying puts the yeast in a sort of hibernation so it lasts much longer. Unopened, packets of instant and active dry yeast should last 2 years.
Red Star Yeast, for example, puts the “Best If Used By Date” for their dry yeast at two years from the date the yeast was packaged. Once opening dry yeast, they recommend using the yeast within 4 months if it was kept in the fridge or 6 months if it was kept in the freezer.
Can You Use Expired Yeast?
Yeast generally doesn’t go bad in the sense that it becomes dangerous to eat. Rather, when yeast goes bad, it means that the microorganisms have died and will no longer help the dough rise.
It varies depending on the storage conditions and strain of the yeast, but you can expect yeast to lose 10-25% of its viability per year at 68 degrees F (20C). At higher temperatures, the yeast will die even faster.
However, there are plenty of accounts of expired yeast still working years after it expired. I even heard one story of dry yeast working fine 13 years after its best-by date.
Tips for Using Expired Yeast:
- Perform a yeast test before using: Dissolve 1tsp of sugar in ¼ cup of warm water (105-115F). Add one packet of yeast. Within 10 minutes, the mixture should foam up to twice its volume. If it doesn’t, the yeast has lost some of its potency.
- Feed the yeast some sugar first: Put the yeast in a bowl with some sugar and warm water. The yeast will activate, start to eat the sugars, and have a chance to multiply before you add the other dough ingredients.
- Use more yeast: Depending on how old the yeast is, you might need to use much more to get the same rising effect.
How to Store Dry Yeast Long-Term
The key to storing yeast is to keep it away from moisture, heat, and air. These are the elements that could “wake up” the yeast and cause it to start dying off.
Fridge
Unopened packets of dry yeast can last approximately 5 years in the refrigerator. Once the yeast pack or jar has been opened, it should be good for approximately 2 years in the fridge.
The important thing to know about storing yeast in the refrigerator is that the air inside can be very moist. Don’t just put the open yeast packets directly in the fridge: they will start to absorb moisture and die off faster. Instead, put the open yeast packets in an air-tight container first.
Freezer
Storing yeast in the freezer is even better than keeping it in the fridge. The low temperature keeps the yeast cells in “hibernation” mode so they live much longer. It’s not clear how long frozen yeast will last but it should be much longer than 5 years.
Cool Location
Dry yeast is usually packaged in a metallic-type material that keeps out moisture. Air is usually removed from the package with a process called nitrogen flushing. So, yeast packets are already mostly safe from air and moisture. However, the packaging doesn’t protect the yeast from high temperatures.
If you want your instant or active dry yeast packets to last more than 2 years without keeping it in the fridge or freezer, you’ll need to keep it as cool as possible. Don’t keep it near the stove (which tends to get much warmer than other areas of your home), heating vents, or other warm areas.
Sealed Containers
If you can’t keep your dry yeast in the fridge or freezer after opening the package, then you can keep it in a sealed container. These containers will help protect from the elements. For example, you can put the opened yeast in:
- Mason jars
- Buckets with gamma lids
- Air-tight plastic containers
- Sealed Mylar bags
Should I Use Oxygen Absorbers when Storing Dry Yeast?
Yeast will deteriorate faster in the presence of oxygen. Steps should be taken to keep air away from your opened yeast, such as keeping the opened yeast in small air-tight containers without a lot of headroom.
However, you do NOT want to store yeast with oxygen absorbers. The reason for this recommendation seems to be related to how yeast respires differently in the presence or absence of oxygen.
Best Yeast for Long Term Storage
If you want to store yeast long-term for emergency preparedness, it’s really important that you pay attention to the way the yeast is packaged.
I recommend getting yeast which is:
- In smaller packets: While this is ultimately more expensive than buying bulk packages of yeast, it is easier to store because you don’t have to worry about repackaging the yeast once you open it.
- Nitrogen-flushed packaging: Nitrogen flushing removes oxygen from the packaging. This is usually only done on smaller packets or jars of yeast. For example, Red Star’s 3-pack strips and 4oz jars are nitrogen-flushed but their 2lb bags of yeast are not. Fleishmann’s doesn’t give any info about whether their yeast is nitrogen-flushed or not.
- Sturdy packaging: Ideally you get the small packets of dry yeast which are packaged in metal-like materials which keep out moisture. If you must go with a vacuum-sealed package, make sure the material is thicker and has a strong seal.
Below are some recommendations for dry yeast in small packets which have been nitrogen-flushed.
- Red Star Active Dry Yeast (Pack of 3)
- Pakmaya Dried Yeast
- Red Star Active Dry Yeast (4oz)
Alternatives to Yeast
Instead of worrying about the long-term storage of yeast for emergencies, you can also look at yeast alternatives. Check out these posts for more info:
https://extension.usu.edu/preserve-the-harvest/research/cooking-food-storage
https://www.homebrewersassociation.org/forum/index.php?topic=28325.0
https://cooking.stackexchange.com/questions/2532/does-active-dry-yeast-really-expire
https://pdfs.semanticscholar.org/d25e/e8b7ebe576104a28f6779a43b9331ec9c670.pdf
https://www.journals.ac.za/index.php/sajev/article/view/2327
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5349206/
https://onlinelibrary.wiley.com/doi/full/10.1111/1541-4337.12445
https://homebrew.stackexchange.com/questions/22863/lallemand-says-their-dry-yeast-does-not-require-aerated-wort-should-i-aerate-an
Diane, If you make sourdough starter, both it and the discard can be dried in the oven on proof, crushed then sealed with a vacuum sealer.
Line a baking sheet with parchment with a layer or two of paper towels under it – parchment does allow moisture to penetrate and the paper pulls it away. Spread a thin layer over the parchment. Place the sheet in the oven on proof or with only the light on for a couple of days until it’s brittle dry. Then break it, pulverize it or process it into dust.
To reactivate, put some into a bowl, add an equal amount of water and flour, a little pinch of sugar and combine to make a paste. Cover and wait. Add equal parts of flour and water every 12 hours. Then proceed as when maintaining starter. Note that new starter will not produce a strong rise. It takes about a week of feeding/discarding to strengthen it for a nice loaf of bread.
I’m experimenting with using an OA for the dried starter to see if sourdough yeasts react as do commercial yeasts. If it won’t reactivate after 3-4 feedings, then I’ll know and then I’ll then let you know.
Rye makes the most robust starter and can be used to “seed” wheat or unbleached white flour starters. After a few feeding/discard cycles, the rye will be long gone and only the yeasts in the flours used to feed it will be dominate strains. Store some fine rye flour for just that purpose.
Dave
Great info!
Question: is it viable to store the small yeast packets in Mylar with OAs? Or do the OAs affect the yeast even through the packets?
Great article! Thank you! Question: is it a good idea to store dried sourdough starter in an airtight container with either OA or moisture absorbers?
Ideally, store it in the freezer. If you can’t, then store it without an oxygen absorber or moisture absorbers in an airtight container. But, an even better solutioin is to make your own starter. There are instructions here: https://www.primalsurvivor.net/make-bread-without-yeast/
In 2020 when everyone was hoarding toilet paper, I was hoarding bottled yeast, flour and sugar. We need to eat and prior to everyone hoarding TP I had a whole lot I had bought from Sams Club. My yeast is still in the chest freezer. I pulled one out to make yeasted bread before I decided to go back into making sourdough. I still use the yeast for certain breads and it is still in very good shape, I keep it in the fridge but may put it back in the freezer. I have about 5 jars left in my chest freezer. Still buying flour and sugar.
Could you seal the yeast in a small mason jar with the food saver mason jar attachment? Or just vacuum seal it in a bag?
You can use the mason jar attachment. Just make sure you follow the instructions for powdered goods. There are tons of videos on YouTube. You could also vacuum seal it in a bag. I keep my bulk yeast in the freezer though — it’s the safest spot and works perfectly even after 3+ years.
BTW Diane, this site is Totally AWESOME! Years ago, after purchasing too much instant yeast, I asked my favorite yeast producer about this very thing.
According to Red Star Yeast, when keeping it vacuum sealed and frozen, it will last almost indefinitely. I’ve used it five years or longer without a single failure.
I quickly remove a half pint jelly jar amount for use, then vacuum seal the remainder again and place back into the freezer.
Absolutely no performance problems. However, depending only on powered methods to preserve is folly. If its viability is in doubt, proof it first in a little water and a pinch of sugar. Won’t make any difference in the recipe. If using active dry, always proof it.
If freezing unbaked dough for use later, add 50% more active dry to the recipe to compensate for yeast die-off following activation. A little more yeast only means that a little shorter rise time to fully proof is needed.
Hi. Doesn’t nitogen flushing remove oxygen thé same as using an oxygen absorber? Is it différent somehow? Thanks!
Yes, nitrogen flushing basically does the same thing as OAs. I never recommend it though because it is so much more expensive and difficult compared to OAs. IMO, it really only makes sense for big food production companies and not everyday people.
Lots of good info. Thanks
Very good information , exactly what i was looking for
Thank you