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Rehydrating yeast


King Ruddager

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Last time I bought yeast from a LHBS I asked about rehydrating it and they basically told me not to bother (with ale yeasts mostly) and that it can cause more problems than it's worth.

 

Were they lying to me? What are the supposed risks and benefits of rehydrating yeast?

They are not lying to you just offering their advice.

Rehydrating if not performed correctly will cause more problems than it is worth.

If done as per the instructions on the producers website then it does have benefits in that their will be a greater number of yeast cells that survive to work on your wort. When you just throw dry yeast into wort a significant percentage do not survive or are damaged. Since there are heaps of them in a pack there is still enough to do the job so you will be ok.

I would always rehydrate.

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If you sanitise properly there shouldn't be a problem. I just spray everything with starsan.

 

It isn't a time consuming process. I usually do it when I am chilling the wort and just leave it on the bench covered in cling wrap. You will see it go from the powdery granules to a pasty cream (or creamy paste).

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So what are the potential drawbacks of a rehydration?

 

You do it wrong and damage or kill the yeast.

Wrong water, incorrect temperature or poor sanitation are but 3 potential causes of problems.

Different yeast ranching companies have differing recommendations and if you follow their recommendations you will be fine. You can take generic advice by all means but there appears to be differences in the way the yeast is produced and packaged and that may well mean difference in the way the yeast is pitched.

 

Certainly do not rehydrate in distilled or RO water.

Remember different yeast have their own optimal re hydration temperature. Do not get it too hot and do not allow it to cool too quickly.

Best results will be obtained if the rehydrated yeast gets added to the wort as soon as possible after it is ready.

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I have been rehydrating my yeast on my last 2 or 3 brews. I daresay I have noticed activity sooner than I had when I just chucked it in dry.

 

There wasn't really any reasoning behind it apart from wanting to see what effect it had, and the following: Because I cube my worts and tip them into the FV when I'm ready to ferment one, it creates quite a deal of foam on top of the wort in the FV. The first brew I just pitched it dry and it sat on top of the foam for who knows how long before it got into the wort. That's when I decided to try rehydrating it, and obviously this works much better because it goes straight through the foam into the wort straight away, which can only be a good thing! [joyful]

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Hmm, well at this stage it seems like I'm better off just chucking them in dry. That's just me though because I'm more likely to make a mistake while lost somewhere in the nuances, so keeping it simple sounds better.

 

So, what about stirring? That's supposed to get it started quicker too, right?

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I normally just boil some water, tip about 150mL or so into a pyrex jug, cover with glad wrap and let it cool to room temp (which is basically within the range they recommend for rehydration). Once it has cooled, I throw the dry yeast in and cover it over again, let it sit for about half an hour. Usually I'll see little bits of yeast dropping into the water.

 

The only problem I have is that because of the diameter of the jug, the yeast tends to be like a small "pile" on top of the water and takes ages to actually get wetted by it. I usually just get impatient and start stirring it all in after a while, however I haven't had any problems with fermentation as yet.

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That works, obviously. I dry pitched all my brews before I went all grain and never had any problems with the fermentations.

 

But when I've got 5 inches of foam on top of the wort I am not going to dry pitch on to that because it won't get into the wort and rehydrate until however long the foam takes to subside, which could be quite a while. Besides, I'm not too keen on losing half the cells which apparently happens when dry yeast is pitched into a batch. I wasn't aware of that when I was pitching dry.

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I have never rehydrated yeast. Just gone with the kit yeast or a pack from my LHBS.

 

Probably 40 to 50 brews later and i cant think of one that hasnt kicked off quickly or stalled at half time.

 

Basically i cant see the point, its just another thing to do and something else that can go wrong.

 

Due to my extreme laziness, the KISS principle serves me well in life and also in brewing...oops, sorry Yob, i meant fermenting

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I was a sprinkler in the early days when I was a 'mixer' and 'fermenter'. I did a heap of brews that way with no problems whatsoever.

 

Then I started rehydrating, mainly to try something different, and now it is just part of my routine.

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It's not so bad when you don't have a crapton of foam on top of the wort, which you often don't with kit or extract brews. I always thought it was best to get the yeast into the wort as soon as possible to give it the best chance.

 

I'm pretty much in the same boat as Hairy, I tried it out of curiosity/something different, but when I saw how it just goes straight through the foam into the wort rather than sitting on top of it doing bugger all, I decided to make it part of my routine. Do whatever you're most comfortable with and what works for you I reckon though. There's no hard and fast rules. [joyful]

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It's not so bad when you don't have a crapton of foam on top of the wort, which you often don't with kit or extract brews. I always thought it was best to get the yeast into the wort as soon as possible to give it the best chance.

 

I'm pretty much in the same boat as Hairy, I tried it out of curiosity/something different, but when I saw how it just goes straight through the foam into the wort rather than sitting on top of it doing bugger all, I decided to make it part of my routine. Do whatever you're most comfortable with and what works for you I reckon though. There's no hard and fast rules. [joyful]

Your right Kelse, K & K doesn't result in much foam, so the yeast hits the wort as soon as its pitched, but i read that you AG blokes occasionally have to combat a fair head of foam.

 

in the same position, i would want the yeast in the wort asap

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It's not so bad when you don't have a crapton of foam on top of the wort, which you often don't with kit or extract brews. I always thought it was best to get the yeast into the wort as soon as possible to give it the best chance.

 

I'm pretty much in the same boat as Hairy, I tried it out of curiosity/something different, but when I saw how it just goes straight through the foam into the wort rather than sitting on top of it doing bugger all, I decided to make it part of my routine. Do whatever you're most comfortable with and what works for you I reckon though. There's no hard and fast rules. [joyful]

Your right Kelse, K & K doesn't result in much foam, so the yeast hits the wort as soon as its pitched, but i read that you AG blokes occasionally have to combat a fair head of foam.

 

in the same position, i would want the yeast in the wort asap

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Yeah, it's just because I tip the cube of wort into the FV from a height, in order to splash it around to oxygenate it. But yea it does result in a fair whack of foam. The first AG one I did dry pitch it and it just sat on top of the foam[lol] so I thought hm... I'll give rehydrating a crack next time. It did ferment ok though and had no problems with it.

 

Sometimes with kit brews I would get some foam, not like these AG ones but still too much for my liking, so I'd just hold the spoon under it while the whirling wort spun around and catch a lot of it and get rid of it before pitching the yeast. But yeah, had no problems dry pitching.

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The foam pile is a good thing! This means you have oxigenated your wort ready for pitching. K&K or AG your should really have a big foam pile on your wort before you pitch. This truly is the important factor when it comes to healthy yeast and active ferment. whether you pitch dry or not is secondary to an oxigenated wort. I always whip my wort with a spoon up to a lather before and after (re-hydrating) pitching.

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