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Viability of expired dry yeast

I am planing to brew NB’s Dry Irish Stout later this week. Didn’t order the WY 1084 because I thought I still had some harvested yeast. The harvested yeast I had was WY 1098. Should have checked before placing the order. Alternate yeast is S04. I had a packet in the frig with an expiration date of February 2014.

I rehydrated the yeast in one cup of 90°F well water. Had a half inch thick krausen ten minutes after sprinkling the yeast on the surface of the water. Few minutes later stirred the creamy mixture and added it to 1400 ml of 1.020 wort. This morning the starter wort is completely fermented out at 68°F.

I may decant and pitch as is or feed the yeast 500 ml of 1.040 wort about 8 hours before pitching into the stouts wort.

Planned fermentation temperature with this yeast is 62° to 64°F to ferment clean.


Dry yeast is amazing. Back in March 2017 I used a packet that expired December 2010. Started right up!

I tried going to the Danstar Lallemand site to look up an article about the tests they were doing on yeast viability. Remember that they were finding good viability past the normal two year expiration date with refrigeration of the yeast. Lallemand has a new site. Hopefully “Articles” will come back.

I think you have it exactly right… you just need to "coax’ the yeast abit, and just like magic, they will come back to life… Whats the longest you’ve let your harvested yeast sit before rebuilding it for use? Sneezles61

I never even look at the date on dry yeast. Keep it in the fridge and it will outlast you. I don’t rehydrate it either :smiling_imp:

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@flars was working with a package that was three years past it’s expired date. So maybe making a starter with dry yeast is the only way to do this when the dry yeast is move than three years past it’s expiration date. For recently expired yeast, there might be a simpler option (as long as one has a backup plan).

I have a couple of packets of Windsor that are just past their expiration date (Nov 2016). I brewed a batch of brown ale using this yeast in early March using my current process for pitching dry yeast (and a backup packet of S-04 :slight_smile: ). The Windor yeast started up just fine. A couple of early bottles taste appropriate (browns are better to me if they bottle condition 4-6 weeks). Nothing special about the pitching process - remove it from the refrigerator, let it warm overnight to ambient room temperature (~ 62*) in it’s package, sprinkle it on the wort.

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I agree with you. I don’t use dry yeast much, and like to tinker with liquid yeasts and an initial starter to be broken down for subsequent uses. I don’t have to be as mindful to some of the costs, yet, its more of how well can I take care of the yeast… I like to see how long I can expect it to go… Sneezles61

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