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How Do I Know My Pitch Rate From Harvested Yeast?

So for my next beer I plan on harvesting and washing the yeast after primary fermentation. I have watched several videos so I think I understand the process. What I don’t understand is how I am supposed to know how much yeast is in that mason jar? It seems like there is way more yeast in the jar than what was in the original vial. Also, I have read that I am supposed to make a started with the harvested yeast before pitching into the next batch. How do I know whether or not I am over pitching?

Without any sort of microscope or yeast lab capabilities it’s going to be really hard to accurately get an idea of the density and viability of your slurry and in turn the cell count. MrMalty and BrewersFriend both have slurry options for calculations but both take density as a parameter and BrewersFriend doesn’t even consider viability of the slurry.

I’ve yet to repitch from harvested yeast so I’m kind of curious what others say. I know most people’s SOP is to pitch 1/3 of the slurry for ales and 1/2 for lagers but this is within a short time after harvesting. If the yeast was sitting for a few months you have to assume your viability has gone down significantly.

[quote=“mattnaik”]Without any sort of microscope or yeast lab capabilities it’s going to be really hard to accurately get an idea of the density and viability of your slurry and in turn the cell count. MrMalty and BrewersFriend both have slurry options for calculations but both take density as a parameter and BrewersFriend doesn’t even consider viability of the slurry.

I’ve yet to repitch from harvested yeast so I’m kind of curious what others say. I know most people’s SOP is to pitch 1/3 of the slurry for ales and 1/2 for lagers but this is within a short time after harvesting. If the yeast was sitting for a few months you have to assume your viability has gone down significantly.[/quote]
If you can make your next brew day coincide with the date you rack the beer off the yeast cake you save yourself some trouble. Pour out half the cake and then rack the new beer right onto the other half in the fermenter. If the beer is 1.80 or more I might use the entire cake.

Also a time saver…don’t wash the yeast. It’s believed by most now to be a waste of time and actually could be detrimental to your goal of keeping the largest number of healthy viable yeast. If you search this forum you’ll find many threads on this subject and links to test results to support not washing.

If I brew within a couple of weeks of harvesting I’ll use about 1/3-1/2 the mason jar without a starter. If it’s a beer over 1.70 or so I’d probably make a starter for a repitch. Longer than a month I usually make a starter. I use the above mentioned tools to calculate starter and slurry volumes based on harvest date and projected viability.

edit for additional comment:

You can see my methods are very scientific by the use of words like, could, might and usually…

So it sounds like I’m going to pitch and pray?

This is not scientific; but what works for me:

For Ales -

I keep a sanitized, wide mouth, quart jar with StarSan in the fridge all the time. When racking to kegs and I want to save the yeast, I shake, pour out the StarSan and then submerge the entire jar and lid in StarSan while I am preparing my kegs, etc.

I then save enough yeast to fill that quart jar.

On my next brew day, I split the quart of slurry between my two fermentor buckets (I brew 10 gallons at a time). I always use within a month. If I do not use within a month, I toss it.

As has been noted elsewhere, you don’t need to wash or rinse the yeast. There is no real need to do so…with good sanitation practices you can even repitch through many successive batches (with my preferred ‘house’ yeast I’ve routinely taken the repitches well beyond 8-10 brews with no washing of the yeast at any stage, and no negative issues whatsoever).

My other rules of thumb:
If repitching 3-4 weeks or less from the time of the original brew, 1/3 of the saved slurry seems about perfect for a standard strength beer; stronger brews will want 1/2 to 3/4 of the slurry. But a little more, or a little less is fine too. Within reason, it is quite simply not all that critical.

I’ll usually dump whatever I don’t need for the ferment into the boil (the old Fuller’s trick…it serves as ‘food’ for the fermentation).

If repitching more than 3-4 weeks after the original brew, I increase the amounts of slurry for the ferment. I’m not brewing commercially so I just eyeball it, and have never had a bad result.
You can get all scientific about it, and if you’re in a commercial environment it is best to do so…but in the end, nature is your friend, as is cleanliness in your brewing practices… The various pitching rate calculators can, however, be helpful on the homebrew level if you brew more less often than every 6-8 weeks. But as a lover of well aged beer (especially a well aged, traditional IPA) and an aversion to running out of it, I rarely wait that long; if I do, I’ll settle for dry yeast as an emergency measure while I take time to reculture up some of the preferred house yeast.

I like the other’s advise, but for a different take, here’s how I keep my Pacman and 1968 strains alive year round. First, I pitch the smack pack at ~1.35, then I dump ~1.055 wort on the cake, then either something fun or I cut the cake as the others advise. When I start running out of kegs, I dump a fermenter and use whatever clings to the walls to reestablish the cake with another mild–I go through a lot of mild.

You’ll notice that the other replies tailored the pitch to conform to a recipe, I take the opposite approach. My recipes are designed–rather, evolved–for cakes. Having done that for years, I don’t stress about pitch rates because I have a solid handle on how certain recipes work with other recipes.

It’s a different way of approaching things, but I find it works well.

[quote=“The Professor”]As has been noted elsewhere, you don’t need to wash or rinse the yeast. There is no real need to do so…with good sanitation practices you can even repitch through many successive batches (with my preferred ‘house’ yeast I’ve routinely taken the repitches well beyond 8-10 brews with no washing of the yeast at any stage, and no negative issues whatsoever).

My other rules of thumb:
If repitching 3-4 weeks or less from the time of the original brew, 1/3 of the saved slurry seems about perfect for a standard strength beer; stronger brews will want 1/2 to 3/4 of the slurry. But a little more, or a little less is fine too. Within reason, it is quite simply not all that critical.

I’ll usually dump whatever I don’t need for the ferment into the boil (the old Fuller’s trick…it serves as ‘food’ for the fermentation).

If repitching more than 3-4 weeks after the original brew, I increase the amounts of slurry for the ferment. I’m not brewing commercially so I just eyeball it, and have never had a bad result.
You can get all scientific about it, and if you’re in a commercial environment it is best to do so…but in the end, nature is your friend, as is cleanliness in your brewing practices… The various pitching rate calculators can, however, be helpful on the homebrew level if you brew more less often than every 6-8 weeks. But as a lover of well aged beer (especially a well aged, traditional IPA) and an aversion to running out of it, I rarely wait that long; if I do, I’ll settle for dry yeast as an emergency measure while I take time to reculture up some of the preferred house yeast.[/quote]

I pretty much follow this exact same advice listed here. I’ve stopped rinsing yeast. A study some guy did and posted on the internets shows when rinsing yeast, you are rinsing away a LOT of healthy, viable yeast. There’s no need for it. Rinsing does more harm than good. And all the other info/practices listed by The Professor is what I follow in terms of timelines and how much yeast I pitch.

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