Used 5 year old dry yeast successfully

[abw73]

I did some searching about using very old dry yeast, but most message threads I found said throw it out, and only a handful said to try it anyway. I stumbled upon a comment from Kevin Lane at Fermentis who said it only loses about 5% viability every year when refrigerated, and about 10% when stored at room temperature.

I had a sealed packet of Safale US-04 dated Nov 2015 that had been refrigerated for years. I brewed in Jan 2021. The yeast was rehydrated for 15 minutes in a cup of 80F water before pitching. Even though the packet said to just pitch it, I still prefer rehydrating. No yeast starter was used. Airlock was bubbling in less than 24 hours, made plenty of krausen, and fermented out. OG 1.045, FG 1.014, flavor came out fine.

Next I had a sealed packet of Windsor dated Nov 2016 that was also refrigerated. Brewed right after the last beer. Rehydrated before using. No starter. Airlock was bubbling in less than 24 hours and had significant krausen. I read this strain has low attenuation. OG 1.054, FG 1.022, so not the greatest, but the beer turned out fine. Something I wanted to note is the packet was rock hard so I thought the yeast was too. It must have been vacuum sealed because the yeast poured fine once opened.

Maybe this will help someone in the future. Instead of all the guessing, an answer from someone who has actually done it.

 

[odie]

not the first time a long expired yeast has risen from the dead...

been my experience with that brand of yeast...vacuum packed and hard as a rock until opened.

 

[BrewnWKopperKat]

Check out the Ingredient Storage (link) page over in the /r/homebrewing wiki/FAQ for additional information. on how to store ingredients.

For LME, Briess has advice on how to store it if one is not brewing immediately.

a comment from Kevin Lane at Fermentis who said it only loses about

When was the comment made? Where did you see it?

edits: links

 

[abw73]

When was the comment made? Where did you see it?

The quote was from a few years ago. I don't remember where I saw it, random google search, but it wasn't here.

 

[RM-MN]

I have seen experimental evidence that dry yeast properly stored really loses only about 2% viability per year but the manufacturer would rather not make such a claim so they claim the 5% loss. In any case, dry yeast stores very well so one can have a backup "viable yeast" in case their preferred liquid yeast is damaged in shipment. This following is copied from Lallemand :

"Dry yeast is very stable with no significant decrease in viability for several years when stored cold and under vacuum. Consistent pitch rates are achieved simply by measuring dry yeast by weight without the need to count cells or measure viability.Typical pitch rate calculators are designed for liquid yeast. Since liquid yeast viability declines rapidly after production, these calculators compensate by recommending higher pitch rates."

 

[BrewnWKopperKat]

Sigh - so many quotes, so few URLs to the source.

Going "slightly" of track, but maybe in a more useful different direction to many readers (e.g. people who often buy kits on sale to use later) ...

source: /r/homebrewing Wiki - Ingredient Storage

Extract kits - If you don't plan to brew immediately, break up and store the components of extract kits separately, as per below.


Dry Malt Extract (DME) - DME stores well. Store protected from moisture and rodents/vermin, and free from excess humidity or heat. DME is very stable, and the only risks are slight darkening with time from Maillard reactions, and more rapid darkening plus caking if exposed to humidity or moisture. Resealing open bags of DME with tape after squeezing out the air is effective, as is transferring the bag DME into an airtight container.


Liquid Malt Extract (LME) - LME does not store well. LME is prone to rapid darkening and change in flavor (for the worse) from oxidation as well as Maillard reactions. LME should be stored very cold to slow this process down. Freezer is best, followed by refrigerator. Try to reduce any head space to slow down oxidation and freezer burn. Ensure that there is enough room for expansion before freezing so your container does not burst.


Active Dry Yeast - Store in the refrigerator. Keeps very well. Storing unopened packs in the freezer is probably fine pursuant to some in-house research conducted by Lallemand. Oxygen, humidity, and heat are the enemies of active dry yeast, and will prevent some yeast from reviving. A refrigerated, vacuum-sealed sachet will last about long as an unopened sachet. An open sachet, folded over and sealed in a sanitary ziploc bag with the air squeezed will be good for about 1-2 weeks per the late Dr. Clayton Cone. *Note: do not sanitize the bag and introduce moisture that way. New, unused plastic ziploc bags are sanitary from the factory.


Commercial Liquid Yeast Cultures [...]


Harvested Yeast Slurry [...]


Yeast Starter - [...]


Hops, dried - Pellets and cones will last a year or longer without dropoff in alpha acid or aroma character if stored either in an oxygen free package (nitrogen-flushed, mylar barrier package, for example) at room temp, or if frozen (with air contact reduced to a reasonable minimum). If you have a vacuum sealer, the best practice is to store dried hops in vacuum-sealed bags or jars in the freezer. If not, dried hops ought to store well at freezer temps in ziploc bags with the air squeezed out. Immersing the bags in water when sealing may apply exterior pressure that will help the air to come out.


Fresh Hops - [...]


Grain, unmilled - [...]


Grain, milled - Milled grain does not rapidly expire notwithstanding some 'old wives tales' from homebrewers to the contrart. Milled grain should be stored in the same way as unmilled grain. If stored well, it should last at least 6 months without signs of degradation per Briess Malting. Roasted, milled grain may be free from degradation up to 12-18 months according to the same source.