Confused by yeast - rehydrate or not?

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K-Dub

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Hi all,

In doing my research it seems that most (including John Palmer) instruct to rehydrate the yeast, pour it into the fermenter and aerate and stir or shake. However, my kit instructions (which I know I should ignore) say to sprinkle the yeast packet on top, leave it and not to stir. I definitely want to stop using kits eventually but I'm taking baby steps and trying to learn as much as possible. Why the difference and which is the better method? Thanks.
 
i am a beginner as well, i am only on my third batch and i slop it in, i splash around and sprinkle and my beers so far have came out good, but i may be wrong, also i always thought air was good for yeast.
 
What people don't seem to realize is that sprinkling it on the surface of the wort and not stirring it for 15-30 minutes, is rehydrating, just on top of the wort as opposed to water. In fact on the fermentis website (safale/saflager yeasts) that is one of the iirc, 3 "recommended" options to do it...You stir (or I just rock the fermenter a bit-usually just carrying it from the kitchen to my brew closet) after the yeast has abosorbed the liquid....(reydrated)

all methods work, it really comes down to a matter of what works for you.
 
I usually pour a bit of boiling water into a cup and then top it up with cold water till it becomes warm, then sprinkle the yeast on top and leave it for 30 minutes before adding it to the fermenter.
 
If its just as easy for you to do both, I would say its better to rehydrate in H2O. Its an easier environment for the yeast to be dumped into.
 
As per John Palmer, and Jamil Z. I now rehydrate my dry yeast every time. The purpose is to fill the cell walls with water before they start eating the sugars. If you rehydrate in the wort, then their cells could become filled with something other than water, which is not as good. My process is:

Little more than a cup of water boiled.
Let cool.
Add yeast on top let sit for 15 minutes
stir yeast into water
Let sit 15 minutes
Pour into cooled wort.

I spend that 30 minutes cleaning up stuff, or organizing notes (or would if I was any good at keeping notes...)
 
+1 on rehydrating in H2O

Until a yeast cell's cell membrane is hydrated it cannot function properly. When that membrane is completely dehydrated, as in dry yeast, there is no control by the organism concerning what is being absorbed.

Pitching dry will kill yeast. Not all of them, but a quite a few are goners. Sure, dry yeast producers account for this by packaging more yeast than you need. But, why not give the wee beasties the best shot to get cranking, dominate the environment, and get to work.

A great analogy is, "I like scrambled eggs for breakfast. I just want to wake up before someone shoves them in my mouth."
 
If its just as easy for you to do both, I would say its better to rehydrate in H2O. Its an easier environment for the yeast to be dumped into.

I dunno, that premise always seems illogical to me....Since it is going to be eating wort, one would think that you would rehydrate it with the medium it is going to be eating.....Just like with a starters, you don't use sugar water but dme....It would seem that you would rehydrate it in the medium.

But like I said, it's apples and oranges, dehydrating, not dehydrating, dehydrating with water or on your wort, they all work.
 
The yeast will ferment the wort whether their rehydrated or not. So the only issue is which method makes a better beer. Has anyone ever noticed any off-flavors that they can attribute to stressed out yeast from not rehydrating?

I don't normally rehydrate. I only do it if I'm repitching in to something with alcohol. Ordinarily I just sprinkle the yeast on top of the fermentor. I usually like to sprinkle it on the foam. I'm not saying my way is the best, but I haven't been convinced otherwise.
 
I've always understood that rehydration in water gives you more viable cells from the package. Something about their ability to control what passes through the cell walls during the process. Other than what I've read (both here on HBT and at yeast mfgr websites) I have no way to prove that, and I always rehydrate so I have nothing to compare it to. But it makes me feel better and I'm happy with my beer.
 
Basically, the dehydration process removes water, therefor your best move is to rehydrate with water. I figure since all three major manufacturers recommend water rehydration, there might be good reasons.
 
Thanks for the feedback, I think I'm going to be rehydrating now. I'm willing to bet the kits just don't add that step in order to not scare off people with too many instructions.
 
I like beerkrump's analogy. I think that it should be considered a "best practice" to rehydrate. Yes, logic tells you that putting the yeast in what its going to be eating makes sense. Rehydrating is more akin to making healthy yeast, not getting it acclimated to a sugar environment.
 
The first time I just sprinkled it straight on top of the cool wort and within 5 hours it was bubbling away and did great. The second beer, I rehydrated the yeast and added it. I had a very slow fermentation and it took over 24 hours for any activity. Not sure about the science behind it, but I am just going to continue to sprinkle the dry yeast straight onto the wort. I don't see any great benefits from rehydrating it.
 
Would it be beneficial to add yeast nutrients? If so when and where should they be added? In the rehydrating bath before the yeast go in, or after? In the wort before or after the yeast goes in?
 
Would it be beneficial to add yeast nutrients? If so when and where should they be added? In the rehydrating bath before the yeast go in, or after? In the wort before or after the yeast goes in?

the austinhomebrew yeast nutrient states to be added to the last 10minutes of the boil.

I have done both, usually i follow the yeast packets instructions over the recipe or kit instructions. US-05 doesn't state to re-hydrate. Nottingham does.

Us-05 in my (very limited experience) is a slower starter and overall is a mild fermentation. Nottingham has been a much quicker starter and an aggressive fermentation. but that could be the yeast characteristics showing thru more than just the re-hydration.
 
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