Rehydrating dried yeast

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adamzworld
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Rehydrating dried yeast

Post by adamzworld » Mon Apr 06, 2020 10:42 pm

Would anyone be able to advise please how critical the amount of water is that you use when you rehydrate packet yeast?

I brewed a Wherry kit earlier and thought it would be better to rehydrate the yeast. I ended up using two packets of yeast and addded them to boiled water that was cooled to around the same temp as the wort. I let it sit for fifteen minutes, stirred, then left it for a further five minutes before pouring it into the wort.

My question is how critical is the amount of water that you use when you rehydrate the yeast as I read afterwards that it should ideally be 4 fluid oz.

TIA

WalesAles
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Re: Rehydrating dried yeast

Post by WalesAles » Tue Apr 07, 2020 7:07 am

adamz,
Read this, conflicting opinions........

viewtopic.php?f=12&t=82077

I`ve never rehydrated dried yeast, no probs on the beer outcome. :D

WA

Uncle Joshua
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Re: Rehydrating dried yeast

Post by Uncle Joshua » Tue Apr 07, 2020 9:23 am

Just sling it in.

adamzworld
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Re: Rehydrating dried yeast

Post by adamzworld » Tue Apr 07, 2020 11:07 am

WalesAles wrote:
Tue Apr 07, 2020 7:07 am
adamz,
Read this, conflicting opinions........

viewtopic.php?f=12&t=82077

I`ve never rehydrated dried yeast, no probs on the beer outcome. :D

WA
Thanks WA, sounds like opinions are divided then! I do normally just chuck it in dry, but this time I was using a kit with a best before date of Aug 2018 so thought hydrating the yeast would give it a bit of a kickstart. I used the kit yeast, plus a pack of Gervin yeast bought from Wilko last year.

Will let you know how it turns out, but knowing how long Wherry takes, we might all be out of the current lockdown by the time it's finally ready to drink!
Last edited by adamzworld on Tue Apr 07, 2020 11:09 am, edited 1 time in total.

adamzworld
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Re: Rehydrating dried yeast

Post by adamzworld » Tue Apr 07, 2020 11:08 am

Uncle Joshua wrote:
Tue Apr 07, 2020 9:23 am
Just sling it in.
That's pretty much what I did. I hoping that as the temp of the wort was roughly the same temp as the hydrated yeast mixture that it should turn out okay

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Re: Rehydrating dried yeast

Post by Nitro Jim » Tue Apr 07, 2020 4:30 pm

In Jonathan Palmer's book he suggests that dried yeast supplied with kits is so good these days that there is no need to rehydrate. I've never bothered and I have done 70 kits...
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Re: Rehydrating dried yeast

Post by guypettigrew » Tue Apr 07, 2020 5:39 pm

Nitro Jim wrote:
Tue Apr 07, 2020 4:30 pm
In Jonathan Palmer's book he suggests that dried yeast supplied with kits is so good these days that there is no need to rehydrate. I've never bothered and I have done 70 kits...
Agreed. I don't use kits anymore. When I did, sprinkling the dried yeast on the surface of the wort always worked.

My local homebrew shop at the time told me it was better to sprinkle the yeast on the wort and leave it to sink in rather than stir it in. No idea if that's true, but sprinkling always worked for me.

Guy

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Re: Rehydrating dried yeast

Post by orlando » Tue Apr 07, 2020 6:09 pm

If you have the Yeast book by Chris White of White Labs fame take a look at the section on dried yeast. Then take a look at Lallemande's web site. #-o

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Re: Rehydrating dried yeast

Post by Nitro Jim » Tue Apr 07, 2020 6:37 pm

guypettigrew wrote:
Tue Apr 07, 2020 5:39 pm
Nitro Jim wrote:
Tue Apr 07, 2020 4:30 pm
In Jonathan Palmer's book he suggests that dried yeast supplied with kits is so good these days that there is no need to rehydrate. I've never bothered and I have done 70 kits...
Agreed. I don't use kits anymore. When I did, sprinkling the dried yeast on the surface of the wort always worked.

My local homebrew shop at the time told me it was better to sprinkle the yeast on the wort and leave it to sink in rather than stir it in. No idea if that's true, but sprinkling always worked for me.

Guy
I give the wort a good stirring, sprinkle the yeast on top and then stick the lid on the fermenter as soon as possible.
Beer is my drug of choice.
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No beer, no fun - know beer, know FUN!

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Re: Rehydrating dried yeast

Post by guypettigrew » Tue Apr 07, 2020 6:38 pm

orlando wrote:
Tue Apr 07, 2020 6:09 pm
If you have the Yeast book by Chris White of White Labs fame take a look at the section on dried yeast. Then take a look at Lallemande's web site. #-o

It's your Beer. :D
No, I don't have the book, and don't know the web site. Any chance of a precis, Orlando?

Guy

Ps, the advice from my old LHBS was many years ago!

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Re: Rehydrating dried yeast

Post by orlando » Wed Apr 08, 2020 6:48 am

White claims that up to 50% of the yeast cells can die if they are not rehydrated first. Lallemande recommend it but I've seen research, I think it was by them, that suggested you didn't have to. You will hear anecdotally that it doesn't matter and the opposite. Rehydrating runs a slight risk of either not being done properly and yeast dieing or introducing bacteria. The opposite could be chronic underpitching as a result. Experiment: Split the wort into two fermentors. Pitch one dry, one rehydrated. Ferment in exactly the same way and see what you find.
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Rehydrating dried yeast

Post by LeeH » Wed Apr 08, 2020 10:08 am

^^Sounds like a job for Brulosophy.

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Re: Rehydrating dried yeast

Post by orlando » Wed Apr 08, 2020 11:03 am

They didn't find it did..

This comment is probably the reason and a reasonable conclusion:

"Many of the brewing texts that recommend rehydration were written quite awhile ago, and a lot has changed over the years. It’s entirely possible ingredient quality and standard brewing practices have improved such that the dry yeast of today is hardier and less likely to suffer from the potential negative effects of direct pitching. Alternatively, maybe the different pitching methods did produce a difference and tasters simply weren’t able detect it to significant degree. Either way, with my results corroborating Marshall’s initial findings, I’m inclined to continue skip the rehydration step and pitch dry yeast direct directly into the wort, even if it means slightly longer lag."
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Re: Rehydrating dried yeast

Post by vacant » Wed Apr 08, 2020 12:07 pm

orlando wrote:
Wed Apr 08, 2020 6:48 am
White claims that up to 50% of the yeast cells can die if they are not rehydrated first. Lallemande recommend it but I've seen research, I think it was by them, that suggested you didn't have to.
Yes, Lallemand do seem "a bit on the fence over this" because their data sheets (e.g. for Windsor and Nottingham) state dry pitching is fine:

"For many fermentations, this stress is not significant enough to affect fermentation performance and flavor"

Exceptions are high gravity and sour worts. For such "difficult" ferments they suggest also using a rehydration nutrient.

Fermentis (e.g. Safale S-04) have an E2U logo for yeast were direct pitching is the first option

"Lesaffre know-how and continuous yeast production process improvement generates an exceptional quality of dry yeasts able to resist to a very wide range of uses, incl. cold or no rehydration conditions, without affecting their viability, kinetic and/or analytical profile

(their emphasis)
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Re: Rehydrating dried yeast

Post by mooncat » Wed Apr 08, 2020 4:48 pm

I always rehydrate dried yeast. With an 11gm packet I put in a sanitised bottle and add 250ml of 20c water. I leave for 15 mins for the yeast to start working and then add 250ml of wort and leave another 15 mins and the add to fermentor. 9 out of 10 times the yeast begins working immediately. I ferment under pressure so can see the pressure rising in the fermentor as the yeast becomes active, usually within a few hours, between 4 and 8 hours. I collect the yeast at the end of fermentation and refrigerate. If I use it within two months I let it come up to room temp, usually around 20c and pitch. If older I bring it to room temp and add 250ml of wort and leave an hour the pitch. This also usually results in a fast ferment. With both methods I ferment out from up to 1.050 in 4 to 5 days, a few days longer for higher gravities or lagers. Try it

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