old dry yeast

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Rob_85
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old dry yeast

Post by Rob_85 » Wed Apr 01, 2020 12:54 pm

I have some old packs of dried yeast. These have all been stored in the fridge but are well past their 'best before' date.

- US-05 (bbf 09 2018)
- S-04 (bbf 09 2018)
- T-58 (bbf 01 2015)
- M20 (bbf 07 2019)

Should I bin these or are they still ok to use?

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gr_baker
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Re: old dry yeast

Post by gr_baker » Wed Apr 01, 2020 2:06 pm

Common sense says no but I just chucked two packets of Windsor yeast from 2006 I found under the stairs into a sugar wash I used to make hand sanitiser from. It took off like a rocket

Rob_85
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Re: old dry yeast

Post by Rob_85 » Wed Apr 01, 2020 3:59 pm

Well that's considerably older than my stuff.

Any autolysis off flavours in the sanitiser? :lol:

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gr_baker
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Re: old dry yeast

Post by gr_baker » Wed Apr 01, 2020 4:02 pm

No idea but there's a faint smell of rum when using the sanitiser

Rookie
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Re: old dry yeast

Post by Rookie » Wed Apr 01, 2020 6:41 pm

Properly stored dry yeast only loses about 4% vitality a year.
I'm just here for the beer.

Rob_85
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Re: old dry yeast

Post by Rob_85 » Tue Apr 07, 2020 5:14 pm

Used one of those old S-04 packs (re-hydrated) on Sunday, in a OG1039 wort. Started bubbling a bit yesterday and is fully active today.

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seymour
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Re: old dry yeast

Post by seymour » Fri Apr 10, 2020 2:08 am

I bet they're all usable, but if you're worried, just boil up some malt extract for a small yeast starter a couple days before your main brew. This is a recommended "best practice" anyway and will always do more help than harm.

Rob_85
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Re: old dry yeast

Post by Rob_85 » Tue Apr 21, 2020 11:32 am

Beer has been in the keg now a few days and tastes absolutely fine. I'm not picking up any yeasty off flavours - slightly sulphury perhaps but I may have been a bit heavy handed with the gypsum!

guypettigrew
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Re: old dry yeast

Post by guypettigrew » Tue Apr 21, 2020 3:35 pm

Rob_85 wrote:
Tue Apr 21, 2020 11:32 am
slightly sulphury perhaps but I may have been a bit heavy handed with the gypsum!
Not sure there's a real connection there!

Sulphury taste and smells often come from the yeast activity, I think.

Guy

Rob_85
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Re: old dry yeast

Post by Rob_85 » Tue Apr 21, 2020 4:28 pm

Certainly is a connection between gypsum and hydrogen sulfide?

But yes, could well be an off flavour from the yeast. However, I thought this was more of an issue with lager yeasts?

guypettigrew
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Re: old dry yeast

Post by guypettigrew » Tue Apr 21, 2020 5:22 pm

Gypsum is Calcium sulphate. Sulphury smells are usually from hydrogen sulphide. Quite a different thing.

That's the limit of my chemical knowledge!

Perhaps someone else can leap in and help?

Guy

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seymour
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Re: old dry yeast

Post by seymour » Tue Apr 21, 2020 5:36 pm

Sulfur is a totally natural compound from healthy fermentation, especially lagers or cooler ale temperatures. It is typically blown-off or masked during active fermentation, though. So if you're still tasting too much in your finished beer, you probably just didn't allow the yeast enough conditioning time before chilling and kegging. It's not a terrible beer fault though, a little is actually desirable in Pilsners and other classic world styles.

guypettigrew
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Re: old dry yeast

Post by guypettigrew » Tue Apr 21, 2020 5:56 pm

And it goes away, given time. Did Seymour sort of say that?!

Mind you, there are things you can buy to get rid of it.

It troubled a few brews of mine a while back. Noticeable during fermentation, but neither smellable or tasteable in the final beer, thank goodness!

Never found out what caused it, then it never happened again.

Guy

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seymour
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Re: old dry yeast

Post by seymour » Tue Apr 21, 2020 11:53 pm

Rob_85 wrote:
Tue Apr 21, 2020 4:28 pm
Certainly is a connection between gypsum and hydrogen sulfide?
But yes, could well be an off flavour from the yeast. However, I thought this was more of an issue with lager yeasts?
guypettigrew wrote:
Tue Apr 21, 2020 5:22 pm
Gypsum is Calcium sulphate. Sulphury smells are usually from hydrogen sulphide. Quite a different thing.
That's the limit of my chemical knowledge!
Perhaps someone else can leap in and help?
Guy
I just found this in my World Brewing Academy notes:
Calcium Sulphate (gypsum) is one of the two common calcium salts that brewers use. Calcium sulphate/sulfate imparts drier, more bitter flavours in beer It also acts as a source of SO2 and H2S, formed during fermentation giving beer a sulfury note. SO2 smells like burnt matches. H2S smells like rotten eggs.

So Rob, sounds like you're right and you could reduce the sulfur smell in your finished beer by simply dialing back the gypsum addition. It's much harder to eliminate for people who simply have higher concentrations in their local water supply. And Guy, you're right they're different things but the one produces the other in beer. Cheers!

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Mashman
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Re: old dry yeast

Post by Mashman » Wed Apr 22, 2020 5:24 am

Two Valleys Brewery

Brewing up trouble

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