Yeast Lifespan

I know I have read it on here before but can't find the thread. How long can you keep yeast in your fridge? I know that any longer than 2 weeks, you must make a starter but I forget how long it is good with making a starter. 2 months? 3 months? 6 months?

I've kept washed yeast about a year or so, I believe, and it worked fine. I make sure my jars are boiled (not just sanitized) and use boiled utensils (like a funnel). I've only had one small jar of washed yeast that I didn't end up using- it might have been ok, but it smelled bad when I opened it so I tossed it.

A lot depends on how the yeast is packaged. Are you asking about smack packs and vials or yeast harvested from a previous ferment? I haven't tried to store harvested yeast for more than a few weeks, but I have successfully activated a couple of old smack packs. One was over five years old and the other three years. I did make starters with each. They both made very good beer.

Yes, I am talking about harvested yeast. So if you are completely sanitized you can keep it for about a year as long as you make a starter with it prior to pitching into your fermenter?

TommyBoy said:

Yes, I am talking about harvested yeast. So if you are completely sanitized you can keep it for about a year as long as you make a starter with it prior to pitching into your fermenter?

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That's been my experience- not just sanitized though, but almost sterile. (I say "almost" because I definitely don't live in a sterile environment, but boiling the jars, etc, seems to kill more microbes that have a chance to infect than a simple sanitizer.) I have the yeast in the kegerator, so it's kept cool but quite a bit above freezing (39 degrees), without frequent door openings.

Like I said, one had a bad odor, which I threw out. The rest have all been fine. I'm very careful with the washing, and save only nice looking yeast without trub. I never used any yeast that was older than about a year, and that was only a couple of times. Usually, I use it within 3-6 months.

I know that there are brewers who freeze slants, and keep yeast much longer but I don't have any expertise at all with that.

I used month old washed Nottingham (about 2 cups) and a re-hydrated pack in a split 10 gallon batch. The Nottingham took off first. (I ended up liking the US-05 half better.) I used month old S-04 once too and it took two days to take off. Different strains seem to have different shelf life. I would think that many of the liquid only strains will have the shorter shelf life but I've alway used a starter with them.

Until the band of yeast in the jar is no longer creamy off white, but gray looking..That could be a month or two years depending on how sanitized you were were in harvesting, how healthy the yeast was when you captured it, any number of things....but if it looks gray, then it has died.

FWIW, Boiling is only sanitizing. You need to hit a boiling temp of 250F to be sterile, for which you need a pressure canner/cooker or autoclave.

You can also sanitize them dry, in the oven. Start with a cold oven, 350f for an hour will kill anything and everything on them. Turn the oven off, let it cool completely, and take the jars out.

PseudoChef said:

FWIW, Boiling is only sanitizing. You need to hit a boiling temp of 250F to be sterile, for which you need a pressure canner/cooker or autoclave.

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That's true- I have a pressure canner that gets to 240F (but I'm not sure it actually gets to 250F). It's probably a bit of overkill, but if I'm planning on saving yeast I spend a little more time and try to be as aseptic as I can. It's not possible to be sterile at my home- but I try to do the best I can. For keeping short term, sanitizing the jars is probably enough.

The yeast washing illustrated sticky instructs to boil the jars, and I would guess that is what many people do.

I used Muntons ale yeast packets that had been in my basement for at least 11 years from when my dad was brewing. It was alive, I used it, it fermented my beer. Beer tastes great with a nice head! I dont know if I was lucky, or maybe yeast lasts longer than you think.

cheschire said:

I used Muntons ale yeast packets that had been in my basement for at least 11 years from when my dad was brewing. It was alive, I used it, it fermented my beer. Beer tastes great with a nice head! I dont know if I was lucky, or maybe yeast lasts longer than you think.

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But that is dry yeast, right?

I've hear/read some breweries have bee using the same yeast for over 200 years...adding nothing...