Does stirring the rehydrated yeast decrease viability?

I am wondering if not letting the yeast settle down to the bottom of the glass (when poured in the glass for rehydration), lowers viability? I also question if I should stir at all at any stages of rehydration?

 

Stirring breaks up clumps of yeast and allows the yeast to rehydrate equally. Continuous stirring will not affect viability, but it is not necessary. Stirring before pitching will resuspend the yeast for easier pouring.
I tried to upload the .pdf for Fermentis SA-05, but it is a tiny bit over sized for this forums maximun. Go to the Fermentis site for hydration technique. They do recommend stirring for 30 minutes, but I think this is if you are rehydrating pounds of dry yeast.

 

Charlie's book says to not stir it, although I don't recall there being an explanation as to why not.

 

Why do you think so many buy/build stir plates? It won't hurt it,so stir away. I stir it up into a cream right before pitching.

 

Well, it is actually not the stirring itself, but the fact that I poured the yeast in a glass of sanatized water and instead of letting it sit there for 15 minutes, I stirred it. But your point makes sense....probably it is all fine.

 

I see. What you did wasn't harmfull,just the Flintstone version of a stirplate. Just leave it to rehydrate for 30 minutes,stir it up well,& pitch.

 

Stirplates and re-hydrating dry yeasts are different procedures.

You do not use a stirplate when re-hydrating dry yeast.

To the OP no stirring has no detrimental effect when hydrating unless you use an electric mixer.

 

As the directions say on dry yeast. Its pour the yeast on top of the water cover wait 15 minutes then stir. Adding the yeast to the water and stirring it and immdiatley adding it to the wort isnt ideal but it may be slightly a little better than just pitching dry. People pitch dry and seem to have no complaints also.

But ideally as for hydrating you want to add some of the precooled wort after stirring for 10-15 min. to get the temperature more closer to that of the wort before you pitch.Thats the proper method for "viability". As to limit yeast shock/stress. I dont always do that though, I usually just hydrate it and pitch within 30 min. I also probably generally use more dry yeast than I need so thats why I dont stress about it and as long as they turn out great then thats better if that method works better for you. Just make shure you write down every detail of brewing when you do this because it may be hard to tell what exactly made your beer better from batch to batch.

 

The tempering process (adding some cooled wort) also is supposed to increase the sugar content of the slurry so that the shock of going from 1.00 water to ~1.06+ wort does not shock the yeast as well. I have been pretty lax in the rehydration for dry yeast, and have yet to temper it.

 

I don't think it'd really matter if you used a stir plate for rehydrating. Yeast is yeast when you take'em swimmin. The stiring action is just to keep them in suspension,the thought being that they'll reproduce more readilly that way vs settled.

 

I pitch my yeast dry, pour it in nice and slow into the carboy. I do roughly about 6G batches, the typical dry packet of yeast is good for something like 10G or so, you end up pitching at higher rate so your fine regardless.

 

Err, it is? I always understood 1 pack of dry yeast per 5 gallons...

Just for fun I loaded up the Mr. Malty yeast calculator and it says for 10 gallons of 1.060 OG beer, you'd want exactly 2 packs of dry yeast (11.5 grams per pack).

Playing around with it some more, it says for 5 gallons of a 1.050 OG beer, you need .8 packs of dry yeast... so yeah, you might be over pitching a little if you're doing 5 gallons... but not by very much.

 

wanted to comment on the tempering process. I brewed yesterday and after hydrating my Notty yeast @ 100 deg, I used a turkey baster (sanitized) to pull the cooled wort (89 deg) from the kettle. I added 2-3 oz to the slurry in 3 installments, gave it a stir and pitched in the fermenter. So far (14-15 hours) there is some gas release when i vent to carboy so things should be fine but i'm going to be ready with another packet of yeast when i get home from work today just in case. My ferementer controller is reading 64 deg so the cooler temps might be keeping the yeast from taking off.

 

I failed to read the instructions properly on the Nottingham and stirred it immediately, then pitched it after about 10minutes. Took about 24hours in 18C wort but seems to be fermenting now. How’d everyone else get on?

 

You know what is amazing? I've used Nottingham with rehydrating like the instructions say and I've sprinkled it on top of the foam in the fermenter and I've put it into the bottom of the fermenter and poured the wort on top of it and believe it or not, after about 24 hours it starts fermenting. Most of the instructions are based on large brewery practices and with huge quantities they should follow the instructions carefully but with the smaller batches that homebrewers deal with it isn't very critical.