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Subject: pitch rate - Wyeast site
Author: attymwilson
Aug 7th, 2012
12:12 pm
I have been harvesting yeast successfully, but I've wondered whether I've pitched too much on occasion, for various reasons. Wyeast warns that you shouldn't have too low or too high a pitch rate. At the bottom of this link

http://www.wyeastlab.com/hb_pitchrates.cfm

they say: "Harvested slurry is typically in the 40% to 60% solids range. A home brewer can make a rough estimation based on this information and combined with consideration for all other factors involved (trub content, age of yeast, strain, original gravity, etc.)."

What does this mean? How does the percentage of solids correlate with pitch rate, discussed higher on the page? And the figures they use under the picture have numbers above the percentages, such as "1.0 E9." Does this mean 1.0 x 10^9 = 1 billion? If so, what does this refer to? It can't be pitch rate. Is it total cells?

In general, for those of you who harvest yeast, how do you decide how much to pitch?

Thanks guys. Mark

Subject: Re: pitch rate - Wyeast site
Author: Dunkelbier
Aug 7th, 2012
12:20 pm
Mark - I think it's pretty difficult (but not impossible) for a homebrewer to overpitch. When I reuse a yeast cake I typically use probably 2/3 of the cake by scooping it out of the fermenter with a sanitized ladle. This has worked well with Notty and SA05 for me. I usually see airlock activity within 2-5 hours when I reuse the yeast. Also, I've never had an issue with flavors, solids, etc.

I've never used the same yeast for more than 3 batches.

Not sure if that helps or not. I was nervous the first couple times reusing the cake, but now I do it whenever I can. It saves a little cash and morre importantly the fermentation takes off a lot quicker because you start with some many more cells thereby reducing the chance of an infection.
Subject: Re: pitch rate - Wyeast site
Author: brewboy_BB
Aug 7th, 2012
12:35 pm
I usually try and pitch about a cup of stored slurry for a 10 gallon batch, unless I just made a starter, then it's more like a quarter of that. Nobody really knows how many viable cells you have in a given amount of slurry and for that reason Mr. Malty and other calculators are nothing more than a WAG when it comes to pitching rates.

I know that I've both over pitched and under pitched and I can't tell that it makes that much difference.

"And the figures they use under the picture have numbers above the percentages, such as "1.0 E9." Does this mean 1.0 x 10^9 = 1 billion? If so, what does this refer to?" Yes, you are correct on what the number means and it represents the number of cells in each of those vials. I think they're giving you a visual representation of what a billion or more cells looks like. Keep in mind that isn't "unwashed" slurry like you'd get from the bottom of you fermenter.

If you really want to know what your slurry contains, here's how to do it right. All I can say is, prepare to spend some money on a good microscope.


http://www.vivo.colostate.edu/hbooks/pathphys/reprod/semeneval/hemacytometer.html
Subject: Re: pitch rate - Wyeast site
Author: Oly
Aug 7th, 2012
2:02 pm
"In general, for those of you who harvest yeast, how do you decide how much to pitch?"

MrMalty.com pitching rate calculator.
Subject: Re: pitch rate - Wyeast site
Author: brewboy_BB
Aug 7th, 2012
2:12 pm
If you have 11 gallons of ale wort at 1.056 and you're using yeast that's a couple of month old, Mr Malty says you need just over a 1/2 gallon of slurry.

I say bull$hit. That's way more than you need. I might pitch 2 cups in that example.
Subject: Re: pitch rate - Wyeast site
Author: Oly
Aug 7th, 2012
2:23 pm
"If you have 11 gallons of ale wort at 1.056 and you're using yeast that's a couple of month old, Mr Malty says you need just over a 1/2 gallon of slurry.

I say bull$hit. That's way more than you need. I might pitch 2 cups in that example."

Yes, I'd say it's ill-advised to pitch a 1/2 gal of old cells. Most of those cells are dead, the large amount of recommended pitch is to ensure a proper number of viable cells. The dead cells are likely to lead to less than ideal flavor.

The better approach would be to take a smaller amount of the slurry, and work up a starter to create new slurry with mostly viable cells, and to target the number of viable cells that MrMalty recommends.
Subject: Re: pitch rate - Wyeast site
Author: MMMBREW
Aug 7th, 2012
4:07 pm
As far as pitching rates go, and my two cents: I find that way way too many brewers underpitch. It is pretty tough to overpitch, so I'd err on the side of using more slurry or a bigger starter if in doubt. There's enough evidince out there to know that pitching one tube of white labs yeast into say, a 1.070 wort just won't get the job done. Lag times can suffer, the yeast can stress, and a lot of times there will be lots of left over sugars that were never fermented. I've had good success pitching fairly new slurry into new wort. I have never used a starter with stored slurry, and it takes off like a rocket everytime. For big beers that's my go -to process.

I don't know that i'd even try to work with two month old slurry. I know you can use a starter to generate new viable cells, but why risk it? I'd rather spend a little bit more money and know that my beer is going to be great than rick having off flavors or under attenuated beer.
Subject: Re: pitch rate - Wyeast site
Author: EricHa
Aug 7th, 2012
4:09 pm
another thing to do is save your old yeast that you no longer want to pitch... you can use it as yeast nutrient towards the end of the boil.
Subject: Re: pitch rate - Wyeast site
Author: attymwilson
Aug 7th, 2012
5:06 pm
This is all very helpful, thanks guys.

My practice has been that wash and save slurry from a primary in 1/2 pint mason jars, put them in the fridge, and then I make a starter when I want to use a jar. I typically have about 1/2 inch of yeast in the bottom of each mason jar, which then gets pitched into the starter. I have no idea how much yeast I then get out of the starter, but I have always cold-crashed the starter, discarded the beer on top and pitched all the yeast at the bottom of my starter vessel. Anyone think it's worth pouring my starter into one of those vials and then cold crash the vial to estimate how many cells I'm pitching into the actual wort?

Thanks again, Mark
Subject: Re: pitch rate - Wyeast site
Author: DConn
Aug 7th, 2012
5:45 pm
One of the possible consequences of overpitching is increased ester production. Both Dr. Clayton Cone of Lallemand and Neva Parker of WhiteLabs have talked about that. The same enzyme, acetyl co-A, is responsible for both ester production and yeast growth. If it's doing one, it won't be doing the other. So if you overpitch to the point there's minimal yeast growth, the enzyme will dedicate itself to producing esters. I don't know exactly where the threshold is and I assume different yeasts react differently to pitching rate. But it's at least something to be aware of.
Subject: Re: pitch rate - Wyeast site
Author: MMMBREW
Aug 7th, 2012
6:04 pm
I am aware of overpitching, I just think it's hard to do. You'd really have to go overboard to have that happen. I think underpitching is easier and much more common.
Subject: Re: pitch rate - Wyeast site
Author: DConn
Aug 7th, 2012
7:01 pm
I'm pretty sure I've overpitched a few times, but I have to agree with you that underpitching is a much more widespread problem.
Subject: Re: pitch rate - Wyeast site
Author: MMMBREW
Aug 7th, 2012
9:46 pm
I dont' think I've ever overpitched, but I could see it happening if a brewer uses slurry a lot. I build up cells from white labs vials 95% of the time or so. (Or use dry yeast packets).

But, another question that's often brough up is if underpitching in belgian beers produces more fruitiness or desirable esters? Based on what Denny is saying it could almost be better to overpitch to encourage ester production. I've tried underpitching a couple of times, and I've had much better luck just using a big yeast starter with healthy yeast.
Subject: Re: pitch rate - Wyeast site
Author: DConn
Aug 7th, 2012
9:55 pm
I used to pitch entire slurries, but now I use only 1/3-1/2 of slurry for a "normal" size beer. After trying it a few times, it seemed like my beers turned out cleaner by using only part. For a BW or something like that, I use the whole thing.

As to underpitching to create esters, according to Wyeast it's strain dependent. Their hefe yeasts (wish I could recall the specific strains) do seem to produce more esters by underpitching. But in general, it doesn't seem to be like that for most strains.
Subject: Re: pitch rate - Wyeast site
Author: brewboy_BB
Aug 7th, 2012
11:49 pm
I used to pitch on the entire cake, but now I remove some slurry for future use, particularly if I'm about to fill another fermenter.
Subject: Re: pitch rate - Wyeast site
Author: JimRod
Aug 8th, 2012
3:25 pm
I just saved my yeast slurry from a 10 gal batch. After washing it 3-4 times it turned out to be a half gallon (64 oz) of clean slurry.
Usually I save this in 16 oz mason jars and use 2 per 10 gal batch............

Are you saying if I double or triple the amount of slurry the beer will start to impart esters???? I have used the whole batch before and never noticed anything unusual, but maybe I haven't been paying attention.

What is the correct amount of slurry per 10 gallons ..8 oz, 16 oz, 32 oz. ??? How can you account for dead cells???


Subject: Re: pitch rate - Wyeast site
Author: DConn
Aug 8th, 2012
3:37 pm
Jim, I don't know at what point increasing the amount of slurry will increase the esters. Someone may have quantified that, but I haven't seen it if they have. I'm only aware of the biochemical reasons for it. You could try writing to Neva Parker at White Labs for her input.

As to the correct amount of slurry to pitch, I rely on mrmalty.com. I know that Jamil has done cell counts on slurry to arrive at his numbers, but you just have to guess at the viabilty of your slurry.
Subject: Re: pitch rate - Wyeast site
Author: brewboy_BB
Aug 8th, 2012
3:39 pm
"What is the correct amount of slurry per 10 gallons ..8 oz, 16 oz, 32 oz. ??? How can you account for dead cells???"

That's just my point. Mr Malty's calculator doesn't account for how many dead cells the slurry contains, if it was washed, how it was stored, etc. IMO it's meaningless.
Subject: Re: pitch rate - Wyeast site
Author: MMMBREW
Aug 8th, 2012
3:52 pm
I think the calculator is a good guide to go off of. His research has certainly helped a lot of brewers find a good starting point for the amount of yeast to pitch. If the dead cells are not added to the equation, then you could perhaps add a percentage more slurry to the batch and use that number to experiment with. I think Jamil's calculator has helped many brewers realize they haven't been adding nearly enough yeast to their batches.
Subject: Re: pitch rate - Wyeast site
Author: MMMBREW
Aug 8th, 2012
7:08 pm
I emailed Jamil to see what he has to say about the dead cells and the calculator. He's normally very good at responding to questions or emails, so hopefully he can help with the dead cells question.
Subject: Re: pitch rate - Wyeast site
Author: MMMBREW
Aug 8th, 2012
8:28 pm
Jamil responded quickly to our question guys: It looks like the calculator does include dead yeast cells into the equation. I really don't see any holes in his logic for any part of the calculator.



Yes, the calculator takes into account non-yeast volume. That is
solids, such as protein, hops, dead cells etc. But non-yeast also
includes that portion that is liquid. The looser your slurry, the
lower the yeast density. You need to take that into account.
Generally, it assumes that you rinse your yeast to get rid of most
crud, but you have also ended up with a looser slurry. This factor is
controlled through the non-yeast slider in the calculator. The default
setting is what works for me and seems like it works for a large
portion of the homebrewer population. I probably would avoid changing
that unless you have a good idea of what is in your slurry.

I know most people see a bunch of yeast at the bottom and think it is
all the same density. The reality is that density can change
dramatically over time. So, it could appear to be 50% more or less
yeast in just a few days. Best way is to count cells. Those that think
the calculator numbers aren't correct, probably never did any sort of
cell counting.

JZ
Subject: Re: pitch rate - Wyeast site
Author: brewboy_BB
Aug 8th, 2012
8:37 pm
It's cool that he got back to you so quickly.
Subject: Re: pitch rate - Wyeast site
Author: DConn
Aug 8th, 2012
8:39 pm
JZ is a great guy. In spite of how busy he is running his brewery, he still has a real commitment to homebrewers.
Subject: Re: pitch rate - Wyeast site
Author: MMMBREW
Aug 8th, 2012
8:58 pm
yeah no kidding. probably less than half an hour. I requested that the brewing network interview adam avery and he made it happen pretty quick as well. that's the maharaja show that they did. Jamil has always been a big help to the brewing community. I'm hoping to chat with him at this year's GABF.
Subject: Re: pitch rate - Wyeast site
Author: BryansBrew
Aug 9th, 2012
12:21 am
>Those that think the calculator numbers aren't correct, probably never did any sort of cell counting.

Those that made the calculator think homebrewers actually cell count and run a professional brewery with the same production equipment and requirements.

Fellow homebrewers, use some common sense, not a calculator. if you make a big beer, make a bigger starter. if it's old yeast, make a bigger starter. It's not rocket science- it's an art form, open to interpretation and the variables of life.



Subject: Re: pitch rate - Wyeast site
Author: brewboy_BB
Aug 9th, 2012
12:24 am
That's basically my procedure. The thing is I've had slow starts due to under pitching and explosive starts from pitching too much. Beer turned out fine either way.
Subject: Re: pitch rate - Wyeast site
Author: BryansBrew
Aug 9th, 2012
12:25 am
it usually does. I once used one measly vial of 2 year old yeast in a lager... and it turned out just fine.

Subject: Re: pitch rate - Wyeast site
Author: MMMBREW
Aug 9th, 2012
2:01 pm
While I do think there is a common sense approach to pitching yeast, the calculator and Jamil's other work helped me a couple years ago in a big way. I was pitching a starter in all or most of my beers, but once I really looked into whether I was pitching enough yeast, I realized I probably wasn't. Sure, my beer tasted fine and all that, but once I pitched even bigger starters into my higher gravity beers, I began having much better success. My beer is now cleaner and more attenuated. I think a lot of people could be pointed towards Jamil's yeast book and/or the calculator and would be much better off. Most of the main guys at my lhbs never even use starters and I always feel like their beer could be much better.
Subject: Re: pitch rate - Wyeast site
Author: Hopper5000
Aug 10th, 2012
8:29 pm
Agreed with MMM. From what I have experienced if your planning on your beer being above 7% better make a started with 2 yeast packs/vials instead of one.
Subject: Re: pitch rate - Wyeast site
Author: DConn
Aug 10th, 2012
8:37 pm
Or you can just make a bigger starter with one pack. That's what I do. DME is cheaper than another pack of yeast.
Subject: Re: pitch rate - Wyeast site
Author: MMMBREW
Aug 10th, 2012
10:02 pm
Yeah that works fine as well, but I try to keep my starter gravity lower. I usually try to keep it less than 1.050 or so. I've bumped up most of my bigger beers starters to two vials with 10 oz dme or so. j

Subject: Re: pitch rate - Wyeast site
Author: mroakley
Aug 10th, 2012
10:16 pm
As an example, I'll make a 4L starter (not a high gravity starter) for a RIS using only one vial/pack.
Subject: Re: pitch rate - Wyeast site
Author: bambam26
Aug 10th, 2012
11:12 pm
What if you just save some wort from previous brews will that work as a starter?
Subject: Re: pitch rate - Wyeast site
Author: Longshot
Aug 10th, 2012
11:26 pm
Yes, as long as the gravity is within reason. And of course you may not want to use extra stout wort to make a starter for a pale ale, etc.
Subject: Re: pitch rate - Wyeast site
Author: mroakley
Aug 10th, 2012
11:28 pm
If you use the Australian no chill brewing method, you use wort from your actual batch of beer to make a starter for the beer. Seems kinda cool.

http://www.brewersfriend.com/2009/06/06/australian-no-chill-brewing-technique-tested/

Anyone ever use this method by the way? We have a guy in our club that swears by it.
Subject: Re: pitch rate - Wyeast site
Author: brewboy_BB
Aug 11th, 2012
2:01 am
IMO the no chill method is asking for an infection. You'll might get by with it most times, but eventually it'll get you.

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