28 replies to this topic

[Big Nake]

I have been listening to the Brewing Network's episode on repitching harvested yeast & learned a few things. First, it's clear that I am repitching too much yeast. I just went onto Mrmalty.com's repitching calculator and found that for a 1.050 lager (which I have been making quite a few of...) where I just harvested that day from another primary, I might only require 150-200 ml's of slurry, depending on the thickness of the slurry. I have probably been pitching 500-600mls and I pitch the whole thing, which they say not to do.So... one thing they mention is getting the slurry into a container, decanting the beer and then adding "sterile water" which I assume would be boiled, cooled water. Then they suggest shaking the container and waiting about 10 minutes for the yeast to stratify (word?). Then pitch about 150-200 mls of that and leave the stuff at the very bottom which is typically break material, hop schputz and dead yeast cells. How many of you have done this and am I missing anything? The guys on the show stressed that too little yeast can be bad and too much yeast can also be just as bad. Hmm...

[dagomike]

I think pitching rates are as much art and science. Without cell counting, you're kind almost winging it. I think you want to try doing different things and just compare results, then figure out what works for you. Little variations in pitching should make a significant difference in the resulting beer, but I've tried all bunch of different pitching rates, conditions, and propagation methods, and while the beer was different, I don't think it was a defect. Just different flavor/aroma profiles. I think the key here is not only how much yeast your pitching, as in quantity, but the condition of the yeast. Both viability and vitality. So, I think it's confusing when people say I pitch x-amount, after it sat in the fridge for who knows how long, and who knows what they did on the previous batch and so on.

[Big Nake]

Mike: I completely agree. Without a microscope, how in God's name are we supposed to know what we're pitching? But the show does address that and Jamil mentions that when you pitch in the right amounts, the yeast still grows & multiplies to some extent and that growing & multiplication is what contributes to the pleasing flavor of the beer, in general. Overpitching can cause some issues and pitching dead yeast cells can create off-flavors, etc. I think I will try to pitch according to the calculator and see what happens. I had always heard that it was a remote possibility that homebrewers could overpitch, but I'm beginning to see that it's possible.

[dagomike]

Mike: I completely agree. Without a microscope, how in God's name are we supposed to know what we're pitching? But the show does address that and Jamil mentions that when you pitch in the right amounts, the yeast still grows & multiplies to some extent and that growing & multiplication is what contributes to the pleasing flavor of the beer, in general. Overpitching can cause some issues and pitching dead yeast cells can create off-flavors, etc. I think I will try to pitch according to the calculator and see what happens. I had always heard that it was a remote possibility that homebrewers could overpitch, but I'm beginning to see that it's possible.

Yeah. I'll have to download that. My commute just got longer for the summer with major construction, so I'll need more distractions. :lol:I think my point was just be consistent and adjust from there. I've always found just because something works for someone else, you need to do everything else to get the same results. :)Usually when I repitch, I'll use like 1/2 cup or something. I can't remember the rule of thumb, but something like that. Sometimes I also did Jamil's slurry calculator and I think it was pretty close to the same.

[Humperdink]

So... one thing they mention is getting the slurry into a container, decanting the beer and then adding "sterile water" which I assume would be boiled, cooled water. Then they suggest shaking the container and waiting about 10 minutes for the yeast to stratify (word?). Then pitch about 150-200 mls of that and leave the stuff at the very bottom which is typically break material, hop schputz and dead yeast cells. How many of you have done this and am I missing anything? The guys on the show stressed that too little yeast can be bad and too much yeast can also be just as bad. Hmm...

I have done something really similar to this. I read an article on yeast washing. basically it is the same method that you described here, but repeated then again a second time. This was mainly for storing yeast and ensuring what you are pitching are only the live and healthy cells like you stated. After doing it several times (nervous every time because its a new process to me and I am sterility freak) I found that the beers that I was making were of no noticeable increase in quality. For me the cost/benefit wasn't there. now I just try to get the healthy clean yeast as much as possible and limit the break material into at least one of the fermenters and leave the rest up to ninkasi.C-sounds like that link was a blessing and a curse huh?

[MolBasser]

Trying to calculate pitchrates without actually knowing the cell count is a tough deal.I do know that it is pretty tough for a homebrewer to overpitch.Quite frankly, I would not worry about overpitching. I would try the stratify thing, though I haven't looked into it.How I get around that issue homebrewing is to rack my beer from primary to secondary and then use the yeast from the secondary for pitching. It is much cleaner (no trub and such).Hope that helps.BrewBasser

[Humperdink]

How I get around that issue homebrewing is to rack my beer from primary to secondary and then use the yeast from the secondary for pitching. It is much cleaner (no trub and such).Hope that helps.BrewBasser

This will definitely get you cleaner yeast but is a double edged sword. You're picking the naturally less flocculant yeast so depending upon how long you plan to reuse that pitch, you may want to consider how much you are altering the behavior of that strain. C-

[MolBasser]

Maybe.It hasn't been an issue to commercial brewers who pretty much harvest their yeast for further pitching at the crash cool step.They get around altering the yeast strain by:Limiting the number of generations they use and Harvesting yeast early on in the chilling process.As a homebrewer I don't think anyone is keeping yeast around for enough generations to really alter the strain that much.BrewBasser

[dagomike]

Yeah, I don't think it's that big of a deal. If you were propagating might be a concern just because you're doing multiple steps for each batch instead of none.The real problem comes in when you don't do a seconday.

[MolBasser]

Yep, that would be a problem.I know that many homebrewers never rack to secondary, but I think this is a HUGE mistake. Just me.BrewBasser

[Humperdink]

Limiting the number of generations they use and Harvesting yeast early on in the chilling process.

that's kind of what I was getting at with depending on how often you plan to reuse. A few times shouldn't be an issue, but I know people who use strains ten times or more. Frugal brewing at its best. I always played it safe, took from the primary and tried to limit carrying over break material. Secondaries to me don't pass muster with cost/benefit. I've never looked back after I stopped.C-

[MolBasser]

Most commercial breweries aim for about 20 generations from each yeast propogation. Give or take a few.BrewBasser

[Humperdink]

Most commercial breweries aim for about 20 generations from each yeast propogation. Give or take a few.BrewBasser

Jesus, that's a lot! Would you think that selecting the nonflocculant yeast wouldn't alter the strain over twenty generations? I was definitely led to believe it wouldn't take near that much, but I absolutely defer to your in-brewery experience.How are you going about avoiding using stressed yeast at that rate of repitch? I read (and mind you this is word of mouth not an article or study) after you get above 5% or so the yeast health dwindles and it's ability to fully and properly ferment a batch decreases. Flavor profiles are sacrificed at this point as well... would this, in your opinion, be strongly under the category of homebrew lore?C-

[dagomike]

Jesus, that's a lot! Would you think that selecting the nonflocculant yeast wouldn't alter the strain over twenty generations? I was definitely led to believe it wouldn't take near that much, but I absolutely defer to your in-brewery experience.How are you going about avoiding using stressed yeast at that rate of repitch? I read (and mind you this is word of mouth not an article or study) after you get above 5% or so the yeast health dwindles and it's ability to fully and properly ferment a batch decreases. Flavor profiles are sacrificed at this point as well... would this, in your opinion, be strongly under the category of homebrew lore?C-

It's called a well equipped and staffed QC Lab. Plus if you're brewing a dozen batches a day, you get to know the yeast pretty well. :)From what I've seen the typical Pub brewer is less pitches than that, but some are more loose/fast than others.

[MolBasser]

What Dagon said.The yeast don't really get stressed on a generational level (they will get stressed on an individual fermentation level of course). There are breweries in europe in the hundreds if not thousands of generations with their yeast. The concern with harvesting yeast is the yeasts condition at harvest rather than how many generations it has gone through.But yes, in a commercial setting we can very quickly analyze the quality of our yeast so we (and all commercial breweries) are really on top of that. Heck, it is our livelyhood.BrewBasser

[Big Nake]

Thanks for the replies guys. I was actually out with a couple of homebrewers last night at a local brewpub and I asked them about this. They have both done the sterile water trick and then used most of the harvested yeast, leaving the bottom level there and they have also just dropped new wort into the same old scrungy primary with ALL of the yeast slurry in there and they tell me they cannot tell the difference. I may try using the sterile water, waiting for stratification, decanting and the using 200ml or so of the good stuff, leaving the stuff on the bottom behind and see what it says. My beers made with harvested yeast come out good, but there are times when you taste something and say to yourself, "what is this flavor?". It's not an infection and the beer is certainly drinkable and enjoyable, but there is something there that you did not expect... is it an off-flavor from dead yeast cells or overpitching?? :)Also... what temp should your "sterile water" be when you pour it into the container of yeast? I assume this is boiled/cooled water. Would it make a diff if it was ale or lager yeast? I use quite a bit of both.

[drewseslu]

Most commercial breweries aim for about 20 generations from each yeast propogation. Give or take a few.BrewBasser

Between 6 and 12 generations, longer if someone forgets to order yeast, in this neck of the woods depending on the brewery.

[DaKine]

I usually use only a cup or so, to assure a fast start. Last night I used a fresh whole cake and blow off city. I've never had any other problems by over pitching.

[japh]

Yep, that would be a problem.I know that many homebrewers never rack to secondary, but I think this is a HUGE mistake. Just me.BrewBasser

For every style? I don't use a secondary for my low-gravity beers (Mild, Bitter, etc). I'm really bad about calculating repitching, as in I don't do it at all . I just dump the next batch on the yeast cake, up to 3 batches.

[dagomike]

I gave up secondary a while ago. I might get back to it since I won't be brewing nearly as much and won't be that big of a deal to TLC a batch. Plus I might mess with fining more. Basically though, it's trade off. Time, supplies, and exposure to O2 and bugs. Sometimes it's just better to not mess with it. $0.02.