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-   -   Re-Hydrating Yeast (http://www.homebrewtalk.com/f13/re-hydrating-yeast-94103/)

mangine77 12-22-2008 12:23 PM

Re-Hydrating Yeast
 
Ok. So I've always been a just open the packet of dry yeast and pour it in guy. I've NEVER once had a problem.

Yesterday for the second time ever I rehydrated the yeast, 24 hours later, no fermentation. So both times that I've rehydrated, I've gotten no fermentation within 24 hours. The first time, I never got fermentation and I had to re-pitch after 2.5 days.

Now, I know it's only been 24 hours, but I always have something going before now, so of course it makes me nervous.

So, here's the question. I did re-hydrate my yeast pretty early in the brew day. I boiled 1 cup of water, let it cool to 95 degrees and sprinkled in the yeast. Covered with a sanitized lid. Right before I pitched, I swirled it up with a sanitized spoon, and yes I aerated the wort.

I've since learned that most people do this about 15 minutes before pitching. I did this about 90 minutes before pitching.

Will this make a difference? Is this why I'm not seeing fermentation yet?? Does this extra time of the yeast sitting in the water hurt something?

When would you re-pitch?

Marko73 12-22-2008 12:45 PM

I rehydrate all the time, and the closer to the pitch time, the better control over the temperature. Also, it ensures your dry yeast is activated. I never have proofed the yeast, but have found rehydrating to give me some peace of mind.

From what I understand, the yeast slurry needs to be pretty on target with the temperature of the wort. So if you are pitching the yeast at a different temp than the wort, the yeast might get shocked.

I would repitch just to be safe.

Good luck!:mug:

Tonedef131 12-22-2008 12:49 PM

What temperature is the water you are rehydrating with?

FlyGuy 12-22-2008 01:06 PM

You really do want to rehydrate then pitch immediately, although 90 mins shouldn't be long enough to do kill your yeast and your fermentation. Double-check that you are actually rehydrating at the temperature recommended by the yeast manufacturer. If your thermometer is out, you might be frying your yeast. Otherwise, perhaps it is just a bad coincidence?

mangine77 12-22-2008 01:45 PM

But do you think there is still a chance it will take off?

I also don't have any other yeast laying around. I know that I should.

Homebrew shop is closed today. That means if it doesn't take off by tomorrow morning, it will be at least 48 hours lagtime before I get to repitch.

Should I even bother re-pitching at that point, or dump it???

I've read the chances of a beer coming out good after 48 hours and then re-pitching is rare.

Do you agree?

planenut 12-22-2008 01:54 PM

I think US-05 and S-04 call for 80F +/- 6. I don't know what yeast you used and how 95 degrees would effect it though.

Beerthoven 12-22-2008 01:57 PM

Quote:

Originally Posted by mangine77 (Post 1022210)
... I boiled 1 cup of water, let it cool to 95 degrees and sprinkled in the yeast. Covered with a sanitized lid. ...

It sounds to me like you are rehydrating the yeast with water that is just too hot. I rehydrate every brew and fermentation always takes off fast (< 12 hours).

It can be instructional to look up the manufacturers recommended rehydrating practices. For example, these are the instructions for rehydrating Fermentis SafAle US-05:

"Re-hydrate the dry yeast into yeast cream in a stirred vessel prior to pitching. Sprinkle the dry yeast in 10 times its own weight of sterile water or wort at 27C 3C (80F 6F). Once the expected weight of dry yeast is reconstituted into cream by this method (this takes about 15 to
30 minutes), maintain a gentle stirring for another 30 minutes. Then pitch the resultant cream into the fermentation vessel."

And these are the instructions for rehydrating Nottingham:

"Sprinkle the yeast on the surface of 10 times its weight of clean, sterilized (boiled) water at 30–35C. Do not use wort, or distilled or reverse osmosis water, as loss in viability will result. DO NOT STIR. Leave undisturbed for 15 minutes, then stir to suspend yeast completely, and leave it for 5 more
minutes at 30–35C. Then adjust temperature to that of the wort and inoculate without delay."

There aren't many differences, but there are some, including temperature range and whether to stir or not during the first 15-30 minutes

mangine77 12-22-2008 02:09 PM

I was just following the instructions from Jamil's book and I didn't think to look at specific yeast directions.

So what about the rest of my questions about should I even bother to re-pitch?

Is there anything I can do during the next 24 hours that I have to wait for my homebrew shop to open, that will help?

I have a real turn-off to re-hydrating now. I'm 0-2. I've probably brewed 40 batches by just sprinking the yeast on top, and I've never had an issue. I'm not convinced it makes that much of a difference.

Does anyone else out there still just pitch it dry?

mangine77 12-22-2008 02:25 PM

Quote:

Originally Posted by Tonedef131 (Post 1022247)
What temperature is the water you are rehydrating with?

I followed the advice from the Palmer book that said any dry yeast can be rehydrated from 90-105 degrees. I rehydrated at 95, so I thought that would be good.

lordbeermestrength 12-22-2008 02:39 PM

95F is totally fine.

100dF is actually the ideal temperature for yeast to adsorb water into their membranes...

And Safale actually recommends about an hour of rehydrating prior to pitching.

"Re-hydrate the dry yeast into yeast cream in a stirred vessel prior to pitching. Sprinkle the dry yeast in 10 times its own weight of sterile water or wort at 27C 3C. Once the expected weight of dry yeast is reconstituted into cream by this method (this takes about 15 to 30 minutes), maintain a gentle stirring for another 30 minutes. Then pitch the resultant cream into the fermentation vessel."

I have done this twice now (100dF, 30 mins of sitting, then 30 mins of stirring, then pitch) and have had great results. Safale says to use about 80dF ( 5F) water, but you're totally fine at 95dF.


EDIT: Just thought of something. You didn't use RO water or distilled water, did you? You want to make sure there are some minerals in the water too. I used tap water that has been boiled and then cooled.


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