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General Category => Yeast and Fermentation => Topic started by: paul on November 08, 2012, 06:32:25 PM

Title: Repitching yeast?
Post by: paul on November 08, 2012, 06:32:25 PM
I rarely harvest and repitch my yeast and I wanted to have a reality check on how much to pitch into a barleywine I'm planning.

In the photo below you can see the yeast I harvested from 5.5 gal 1.052 bitter.  I pulled this from the primary about 1.5 weeks after pitching.  I washed once and threw out the bottom 10 or 20% of sediment that looked dark and had hops in it.  I poured what was left into three 1-pint mason jars.

According to the Mr Malty calculator, I need 370 billion cells, which, depending on how I set the Yeast Concentration and Non-Yeast Percentage settings, means I need 87 to 436 mL of yeast slurry...or  181 mL if I just accept the default settings.  If that's right, I'll need to pitch most of the first two jars.  Does that seem right?  I'm just a little surprised that I need most of the yeast harvested from a full batch of beer.

Also, I am a little concerned about the quality of the yeast I have.  Some of the yeast washing videos I looked explained that the good yeast is the light colored layer that settles on top.  I seem to have very little of that.  How much of this is good yeast?

Finally, if I'm not brewing until Sunday, should I do a small yeast starter to refresh this?

Thanks!

(http://www.flickr.com/photos/89851777@N04/8168288606/in/photostream)
Hmmm...the image isn't coming through.  Here's the link:
www.flickr.com/photos/89851777@N04/8168288606/in/photostream (http://www.flickr.com/photos/89851777@N04/8168288606/in/photostream)
Title: Re: Repitching yeast?
Post by: thebigbaker on November 08, 2012, 06:40:23 PM
I would definitely do a starter.  I haven't brewed a barley wine, so I couldn't tell you how much you would need. I'll be interested in what others say, as I'm tossing around the idea of brewing my first barley wine soon, so thanks for posting this question.
Title: Re: Repitching yeast?
Post by: tygo on November 08, 2012, 06:42:47 PM
How old is the yeast?

Regardless of the answer to that question, you're obviously going for a monster, so I say pitch it all.
Title: Re: Repitching yeast?
Post by: davidgzach on November 08, 2012, 06:49:06 PM
Regardless of the answer to that question, you're obviously going for a monster, so I say pitch it all.

+1.  I'd pitch it all.  Make sure you aerate very well too!

Dave
Title: Re: Repitching yeast?
Post by: realbeerguy on November 08, 2012, 06:59:29 PM
Decant & pitch it all.
Title: Re: Repitching yeast?
Post by: paul on November 08, 2012, 07:31:25 PM
How old is the yeast?

It was in the primary 1.5 weeks, and I pulled it from there 2 days ago.  It's been in the fridge since then.
Title: Re: Repitching yeast?
Post by: dimik on November 08, 2012, 07:54:32 PM
Dude, as the others have said, just pitch it all in.
The yeast is still fresh and has not yet gone dormant.
Title: Re: Repitching yeast?
Post by: paul on November 08, 2012, 08:39:55 PM
I guess I was hoping for a little more rigor in the method.  If the answer is, pitch all of it for 5 gallons of 1.10 barleywine, what about 10 gallons?  What if it was 5 gal at 1.08?  See what I'm getting at?
Title: Re: Repitching yeast?
Post by: a10t2 on November 08, 2012, 09:46:08 PM
Clean, packed slurry will be about 4 billion cells/mL. I'd call it 3 billion/mL to account for lost viability, trub in the slurry, etc. So about 120 mL of slurry would be the target. If I'm reading the volume markings correctly, either the left or middle jar should be about right.

Hmmm...the image isn't coming through.  Here's the link:

The text inside the "img" tags has to be the URL of the image (http://farm9.staticflickr.com/8203/8168288606_98931fb564.jpg), not the web page (http://www.flickr.com/photos/89851777@N04/8168288606/). You can get it from the drop-down "Share" menu:

(http://farm9.staticflickr.com/8203/8168288606_98931fb564.jpg)
Title: Re: Repitching yeast?
Post by: davidgzach on November 09, 2012, 05:24:50 AM
I guess I was hoping for a little more rigor in the method.  If the answer is, pitch all of it for 5 gallons of 1.10 barleywine, what about 10 gallons?  What if it was 5 gal at 1.08?  See what I'm getting at?

You're looking for an exact answer for a question that has a lot of variables!  Best to err on the side of pitching more than enough than less than enough.  It's very hard to overpitch to the point where it will affect your beer however it is quite easy to underpitch to where it will affect your beer.

Dave
Title: Re: Repitching yeast?
Post by: paul on November 09, 2012, 07:28:34 AM
So it all looks like pretty good yeast?  Does the darker layer just have a bit more trub and dead yeast?

Thanks for the tip on posting images.
Title: Re: Repitching yeast?
Post by: dimik on November 09, 2012, 07:40:03 AM
OK then. If you want to be more rigorous, I'd suggest making a serial dilution and start counting on the counting slide after you get to around 1 million fold dilution. After that do some vital staining to determine how many cells are alive vs dead. To confirm, I'd recommend plating various volumes of the dilutions on plates and letting them grow out. Then you count the colonies and project the viable cell count. Doing it in triplicate is probably better.
Title: Re: Repitching yeast?
Post by: kylekohlmorgen on November 09, 2012, 10:55:27 AM
OK then. If you want to be more rigorous, I'd suggest making a serial dilution and start counting on the counting slide after you get to around 1 million fold dilution. After that do some vital staining to determine how many cells are alive vs dead. To confirm, I'd recommend plating various volumes of the dilutions on plates and letting them grow out. Then you count the colonies and project the viable cell count. Doing it in triplicate is probably better.

I can't tell if there is sarcasm at play, here...
Title: Re: Repitching yeast?
Post by: jeffy on November 09, 2012, 03:01:11 PM
OK then. If you want to be more rigorous, I'd suggest making a serial dilution and start counting on the counting slide after you get to around 1 million fold dilution. After that do some vital staining to determine how many cells are alive vs dead. To confirm, I'd recommend plating various volumes of the dilutions on plates and letting them grow out. Then you count the colonies and project the viable cell count. Doing it in triplicate is probably better.

I can't tell if there is sarcasm at play, here...

My guess is probably.
Title: Re: Repitching yeast?
Post by: dimik on November 09, 2012, 03:19:32 PM
Nope. This is how it's actually done if you want to get the accurate cell count from which you can project how much of this slurry you'll need.
Title: Re: Repitching yeast?
Post by: tschmidlin on November 10, 2012, 12:48:53 AM
Nope. This is how it's actually done if you want to get the accurate cell count from which you can project how much of this slurry you'll need.
True, except that by the time the plates have grown enough that you can count colonies (1 over night and you can see them if you look closely, 2 over nights and you can count, but 3 overnights is easier) the viability of the culture may be different ;D  If you're going to do the plating I would skip staining, that isn't as accurate.

But unless you are into all of that, I would just do what Sean says.
about 120 mL of slurry would be the target
Title: Re: Repitching yeast?
Post by: dimik on November 10, 2012, 04:52:38 PM
Yeah well, he wanted a really rigorous approach...
Title: Re: Repitching yeast?
Post by: anje on November 10, 2012, 10:26:07 PM
Make sure you change pipette tips every time, too, or your serial dilutions won't be accurate. (Please don't ask how many times I've tried to fudge this and wound up with bad plate counts!)
Title: Re: Repitching yeast?
Post by: tschmidlin on November 11, 2012, 01:08:41 AM
Yeah well, he wanted a really rigorous approach...
True.  :)

Make sure you change pipette tips every time, too, or your serial dilutions won't be accurate. (Please don't ask how many times I've tried to fudge this and wound up with bad plate counts!)
That's also true. ;D
Title: Re: Repitching yeast?
Post by: davidgzach on November 11, 2012, 06:56:39 AM
Yeah well, he wanted a really rigorous approach...

I would still rigorously swirl up all three jars and toss them in...... :)
Title: Re: Repitching yeast?
Post by: dimik on November 11, 2012, 09:21:36 AM
Yeah well, he wanted a really rigorous approach...

I would still rigorously swirl up all three jars and toss them in...... :)

Hehehehe.

Make sure you change pipette tips every time, too, or your serial dilutions won't be accurate. (Please don't ask how many times I've tried to fudge this and wound up with bad plate counts!)

That's assuming he's using micropipettes :D
Title: Re: Repitching yeast?
Post by: anje on November 11, 2012, 09:40:45 AM
Make sure you change pipette tips every time, too, or your serial dilutions won't be accurate. (Please don't ask how many times I've tried to fudge this and wound up with bad plate counts!)

That's assuming he's using micropipettes :D
Yeah, but why dilute into 10 ml when you can dilute into 1? Not to mention, you'd have to have a decent-size set of serological pipettes to do this right, otherwise. 
Title: Re: Repitching yeast?
Post by: ynotbrusum on November 13, 2012, 05:54:22 AM
I'm no microbiologist, but I like the sample on the far left.  To be safe, though, I would decant and dump it all in.