7 month old yeast, opinions???

I have some Lallemand Windsor yeast sitting in the bottom of a gallon jar that has been in the bottom of my refrigerator for the past 7 months waiting on my next wheat beer. Before storing in the fridge:
1) washed two yeast cakes and stored in one jar.
2) made a 1.050 DME starter about 3/4 gallon and once the yeast settled from the first step I decanted the liquid off the yeast and added the starter wort on top of the yeast.
3) I immediately put the yeast in the fridge.
Once the yeast cooled off it did not produce much gas, but over the past couple months there has been no excess co2 and over the past couple of weeks a dark tint has discolored the very top of the yeast cake. I honestly planned on using this yeast before now but due to time constraints I have not been able to brew since May. I would like to use this yeast in the next week or so but if you think this may be a mistake using yeast this old let me know.

I have used yeast that old, I am making a starter with some right now.

Awesome, I really didn't want to throw this away!

Gear101 said:

I have used yeast that old, I am making a starter with some right now.

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I also have the same yeast that is older than that. I placed it in a starter on Christmas eve.

Another issue is that Windsor is not typically a wheat beer yeast, it is a British strain typically used in those styles of beer. Reuse the yeast, but in a different type of beer.

Look, smell, taste, then decide. It shouldn't taste meaty or dead. It should be light tan not brown, and it should have a fresh yeasty smell.

If that's all fine, pitch it into a starter. For my money I'd buy another pack for $3.99, but that's just me.

I misspoke the the type of yeast, it is actually Lallemand Munich. I had just sorted through my yeast in the fridge and that stuck in my head for some reason. I think I'll try letting it warm up and if it takes off in the wort it is in now I'll probably use it, otherwise I don't think I'll mess with it. I usually don't do starters, unless it is ~5 gallons. I would rather use this second gen. yeast rather than starting over with a new package of yeast.

How about option 5) have it tested. I would be happy to do it for free. For details see this:
http://woodlandbrew.blogspot.com/p/normal-0-false-false-false-en-us-x-none.html

That way you will have a much better idea of how many cells you are starting with, how many are viable, and if there is a considerable amount of bacteria. Recovering low viability yeast is simple enough. If it has a fair amount of bacteria there are a several things that can be done as well.

Prepare a fresh starter, and use a scoop (1/4 cup?) of this, aiming for the good stuff on the bottom and staying clear of the dark stuff. It will wake up and take off. Yeast is very resilient.

Yep if it smells fine and doesn't look black or something, go for it. I've regularly used yeast from more than 2 seasons ago and no issues. It's hardy stuff...

allthingsgiant said:

Prepare a fresh starter, and use a scoop (1/4 cup?) of this, aiming for the good stuff on the bottom and staying clear of the dark stuff. It will wake up and take off. Yeast is very resilient.

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Yes, Yeast is very resilient.

The scoop method would probably work just fine, but for me it would be another possible point of contamination. My arm would probably hit the side of the jar or my fingers would dip into the yeast by accident.

If you decant the beer until you are about half beer and half cake, then give it a swirl to homogenize. Then pour that off into whatever you are fermenting in. For a ball pack cell count 500 million cells per ml or gram is reasonable. (for a 50-50 beer thick slurry mix)

Cell counts I have done indicate the only difference in color is the amount of trub and cell density. The bacteria counts are the same, and viability is the same.
Details here:
http://woodlandbrew.blogspot.com/2012/12/yeast-washing-exposed.html


Oh yeah,

"The Practical Brewer - A Manual for the Brewing Industry" suggests a six month cycle for yeast stored in a broth.

And here is some data I have collected on the subject:
http://woodlandbrew.blogspot.com/2012/12/refrigeration-effects-on-yeast-viability.html

WoodlandBrew said:

Details here:

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Fantastic blog. It's well written, and I love that your posts are original content with experiments and data points.

Please keep up the good work. The interwebs need more stuff like this

scottland said:

Fantastic blog. It's well written, and I love that your posts are original content with experiments and data points.

Please keep up the good work. The interwebs need more stuff like this

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Thanks for the positive feedback. That's what keeps me doing what I am doing. New post every other day!

WoodlandBrew said:

Thanks for the positive feedback. That's what keeps me doing what I am doing. New post every other day!

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Just don't get burned out =) I tried to post 8-10 times a month, and just found it to be too much work. I post about once a week these days.

I added you to my google reader, so don't worry, I'll be following.

Thanks for the information, as far as having this stuff tested I don't think that would be cost effective at the moment. Eventually, I would like to have a yeast lab at home but, as it is, my hobbies take up more room than my wife cares for.

Well, here is an update on the 7 month old yeast question. I brewed up 13 gallons of a wheat beer at 1.056 and pitched the 7 month old yeast into 5 gallons of it and let it ferment. After fermentation was complete and before bottling I tasted it and signature flavor of a wheat beer yeast was missing and you could tell the yeast were strained. Not bad, but not good enough either. I went ahead and bottled it and we'll see how it turns out in the long run.