# Homebrewers Association | AHA Forum

## General Category => Yeast and Fermentation => Topic started by: MattyAHA on September 22, 2020, 08:26:07 pm

Title: On average how many pitches can you get from a pint of slurry
Post by: MattyAHA on September 22, 2020, 08:26:07 pm
For example, say you brewed a low to moderate gravity beer 1.040-50 and harvested the yeast/trub into a few pint jars, how many batches of 1040-50 beer can you ferment with one of those jars? 2 batches per pint jar of slurry sound about right?
Title: Re: On average how many pitches can you get from a pint of slurry
Post by: Bob357 on September 22, 2020, 10:07:07 pm
Depends on how thick (concentrated) the slurry is. I figure 1/3 to 1/4 of the cake per batch, depending on the gravity of the beer I'm pitching.
Title: Re: On average how many pitches can you get from a pint of slurry
Post by: denny on September 23, 2020, 08:49:28 am
How long is a piece of string?
Title: Re: On average how many pitches can you get from a pint of slurry
Post by: Iliff Ave on September 23, 2020, 09:11:13 am
How long is a piece of string?

5 units
Title: Re: On average how many pitches can you get from a pint of slurry
Post by: denny on September 23, 2020, 10:29:23 am

How long is a piece of string?

5 units

;D
Title: Re: On average how many pitches can you get from a pint of slurry
Post by: MattyAHA on September 23, 2020, 10:41:49 am
so its an unanswerable question your saying? im a dumb a person excuse me
Title: Re: On average how many pitches can you get from a pint of slurry
Post by: EnkAMania on September 23, 2020, 10:54:19 am
I use one pint for batch, but that may be too much.  I tend to make slightly bigger beers than you.  If it's on the newer end, give a half a shot and see what happens.
Title: Re: On average how many pitches can you get from a pint of slurry
Post by: MattyAHA on September 23, 2020, 10:59:40 am
Thank you, figured that. being its a common practice of homebrewers was just wondering how people know how much to add per 1.040-50 og batches, not sure i why i got "how long is a string" for an answer but ok
Title: Re: On average how many pitches can you get from a pint of slurry
Post by: denny on September 23, 2020, 11:31:07 am
so its an unanswerable question your saying? im a dumb a person excuse me

In a way, it is.  There is so much "it depends" to it.
Title: Re: On average how many pitches can you get from a pint of slurry
Post by: Slowbrew on September 23, 2020, 02:40:28 pm
so its an unanswerable question your saying? im a dumb a person excuse me

In a way, it is.  There is so much "it depends" to it.

Speaking only for myself and my own experience:  Questions like this just lead to ask more questions.

For instance:
How full are the pint jars?
How many jars are there?
How thick is the slurry?
What yeast is it?
Is it clean?  Or is there a bunch of hop matter and trub in it?
Will you make starters?
Store it on plates or in agar filled test tubes?
Then you hit things like viability and infection possibilities.

Basically, if you say you have a string and want to know how long it is, but I can't measure it, I can't answer the question.

"How long is a string?" is snarky but it's one of the nicer ways the point can be made.  "How many licks to get to the center of a Tootsie Roll pop?" also comes to mind.  Others were often used by Dad's, uncles, older brothers that I really shouldn't post due to language and unattainable physical locations of bodily items.

I'll stop, but sometimes a comment is just a sort of funny comment.

Paul
Title: Re: On average how many pitches can you get from a pint of slurry
Post by: a10t2 on September 23, 2020, 03:04:23 pm
While it's impossible to give an exact answer, it isn't like we're completely in the dark here. Very generally speaking, creamy freshly-harvested slurry will be somewhere in the 1-1.5 billion cells per mL range. If it's been stored long enough to separate, roughly double that. Since you're probably looking to pitch ~200 billion cells, a pint of slurry could do around 2-6 batches. I'd probably start with ~1/3 and rely on your flavor preferences to adjust from there.
Title: Re: On average how many pitches can you get from a pint of slurry
Post by: denny on September 23, 2020, 03:34:00 pm
so its an unanswerable question your saying? im a dumb a person excuse me

In a way, it is.  There is so much "it depends" to it.

Speaking only for myself and my own experience:  Questions like this just lead to ask more questions.

For instance:
How full are the pint jars?
How many jars are there?
How thick is the slurry?
What yeast is it?
Is it clean?  Or is there a bunch of hop matter and trub in it?
Will you make starters?
Store it on plates or in agar filled test tubes?
Then you hit things like viability and infection possibilities.

Basically, if you say you have a string and want to know how long it is, but I can't measure it, I can't answer the question.

"How long is a string?" is snarky but it's one of the nicer ways the point can be made.  "How many licks to get to the center of a Tootsie Roll pop?" also comes to mind.  Others were often used by Dad's, uncles, older brothers that I really shouldn't post due to language and unattainable physical locations of bodily items.

I'll stop, but sometimes a comment is just a sort of funny comment.

Paul

Snarky was the last thing I had in mind, so I apologize. I thought it was kind of humorous and light.
Title: Re: On average how many pitches can you get from a pint of slurry
Post by: Saccharomyces on September 23, 2020, 04:00:05 pm
If I were you, I would try to leave the break and dead cells behind in the fermenter that is why I always start with 5.25 galllons.  I rack 5 gallons to a soda keg before taking the fermenter and swirling the dregs into suspension.  The break, hops, and dead yeast cells will settle out within five minutes,   I pour the top-most 300ml into a 500ml Erlenmeyer flask.   That yields about 150ml of thick slurry, which is easily enough for a 5 to 6-gallon batch.  Unless one is brewing every week or two, serial repitching is preferred to splitting a crop into multiple crops.   Serial repitching is definitely the way to go with top-cropped yeast.

This crop was harvested using the technique outlined above.

(https://i.imgur.com/eNKQpg4.jpg)

Notice how it is basically break free
Title: Re: On average how many pitches can you get from a pint of slurry
Post by: Kevin on September 25, 2020, 08:07:09 am
I used the same slurry 5 times this summer. I only stopped at five because the last one I left in the fridge far too long and the resulting beer had a very sour, funky character... and not in a good way.
Title: Re: On average how many pitches can you get from a pint of slurry
Post by: fredthecat on September 29, 2020, 11:01:01 am
While it's impossible to give an exact answer, it isn't like we're completely in the dark here. Very generally speaking, creamy freshly-harvested slurry will be somewhere in the 1-1.5 billion cells per mL range. If it's been stored long enough to separate, roughly double that. Since you're probably looking to pitch ~200 billion cells, a pint of slurry could do around 2-6 batches. I'd probably start with ~1/3 and rely on your flavor preferences to adjust from there.

yup, basically what i was going to say. its one of the only things i guesstimate, because my brewing relies on reusing yeast, ive done it so many times.

i usually pour the yeast into a sanitized 500ml and stick it in the fridge. try my best to drain off any remaining beer on top of the sludge if its too strongly flavoured or very dark then dump most of the bottle into a chilled wort. i dont have any problems with off flavours or hitting an appropriate FG at this ratio of ~400ml slurry to 19 litres of wort.

i think its slight overpitching, so a 1/2 pint to 3/4 pint are probably about right.
Title: Re: On average how many pitches can you get from a pint of slurry
Post by: Bel Air Brewing on October 06, 2020, 02:22:53 pm
We harvest about a quart after each ferment. The entire quart will be pitched into the next brew. This has been going on for months now. Never had any issues at all. Probably 8 or more pitchings of the succeeding yeast generations.
Title: Re: On average how many pitches can you get from a pint of slurry
Post by: coolman26 on October 06, 2020, 04:06:03 pm
Agree on the quart when fresh. I had issues when I would pitch a pint. I tend to divide in half. I try to swirl and leave the junk behind. I try to overbuild my starters and use it.
Title: Re: On average how many pitches can you get from a pint of slurry
Post by: fredthecat on October 06, 2020, 06:40:27 pm
Agree on the quart when fresh. I had issues when I would pitch a pint. I tend to divide in half. I try to swirl and leave the junk behind. I try to overbuild my starters and use it.

how many gallons do you add a pint to?
Title: Re: On average how many pitches can you get from a pint of slurry
Post by: Bel Air Brewing on October 07, 2020, 05:50:55 am
Agree on the quart when fresh. I had issues when I would pitch a pint. I tend to divide in half. I try to swirl and leave the junk behind. I try to overbuild my starters and use it.

how many gallons do you add a pint to?

In our case, we have a quart of solid yeast, with the added wort it will be 1/2 gallon total slurry. This is used for 10 gallon batch sizes.
Title: Re: On average how many pitches can you get from a pint of slurry
Post by: Saccharomyces on October 07, 2020, 05:45:43 pm
In our case, we have a quart of solid yeast, with the added wort it will be 1/2 gallon total slurry. This is used for 10 gallon batch sizes.

If you are pitching a quart of thick yeast slurry into 10-gallons of wort, you are way overpitching.   That is why your crops are pooping out on you.  The suggested pitching rate for one barrel of wort is 1L of slurry.  That rate breaks down to approximately 33ml per gallon, or 330ml for 10 gallons.  The pitching rate for 5 gallons is 5 * 33ml = 165ml of thick slurry.  Overpitching results in reduced new cell production, which over the long haul results in loss of culture viability.  It is always better to underpitch than overpitch when serially re-pitching a culture.  A milliliter of thick slurry contains between 1 and 2 billion cells. The standard practice value is 1.2 billion cells per milliliter.  One liter of thick slurry contains 1.2 trillion cells.  Maximum cell density for 10 gallons is 38 * 200B = 7.6 trillion cells. If we start out with 1.2 trillion cells we only get log2(7.6 / 1.2) = log(7.6 / 1.2) / log(2) = 2.66 replication periods before maximum cell density is reached.  The average batch when pitched correctly goes through 4 to 5 replication periods, which means that the new cell to old cell ratio in the culture is higher than the way you are pitching.  Overpitching may result in a faster onset of active fermentation, but it comes at the cost of new cell growth, which over time degrades the quality of the culture.