Yeast Slurry Experience

[JJack887]

I washed yeast for the first time over a week ago and ended up with about 120ml of thick, compact slurry that's I've kept refrigerated. I've read probably every thread on the subject as to how many cells there are to this slurry, and the info is still sketchy at best -- ("The slurry can have 1 to 4.5 billion cells per milliliter, etc." ...Really? [emoji58]) -- so what I'm asking you guys is this: What is YOUR experience with pitching straight slurry? 120ml just looks like a lot of good yeast to me and it was triple-washed.

 

[bucketnative]

I recently had a similar experience. I pitched about 60 mL of Safale K97 slurry into a 5-gal batch of wit. I want to say that fermentation finished in about 2 days, at least the really active part of fermentation. I let it stay in primary for about 3 weeks before bottling. The results were very good. In fact, when I first used K97 it threw a lot of sulfur during primary (first 4 days), and after 4 weeks of primary the beer still had a slight sulfur nose to it in the bottle. This time around, no noticeable sulfur during airlock activity and no sulfur nose in the bottle.

 

[Morrey]

I recently had a similar experience. I pitched about 60 mL of Safale K97 slurry into a 5-gal batch of wit. I want to say that fermentation finished in about 2 days, at least the really active part of fermentation. I let it stay in primary for about 3 weeks before bottling. The results were very good. In fact, when I first used K97 it threw a lot of sulfur during primary (first 4 days), and after 4 weeks of primary the beer still had a slight sulfur nose to it in the bottle. This time around, no noticeable sulfur during airlock activity and no sulfur nose in the bottle.

Just wanted to tag along on this question as I plan to harvest slurry from a Pilsner fermenting now with WLP800 German Lager yeast. Like you guys, I have read lots of threads but it just seems to be throwing darts in my opinion. Unless we had very specific and expensive lab equipment, how do we really know the vitality and yeast cell volume?

Once I rack off my finished Pilsner, I expect to leave about .5G (two quarts) of beer/yeast slurry in the FV. I propose to swirl that slurry into a thick suspension and pour into two one quart sterilized Mason jars. Cover loosely and store in fridge for later use. I expect a separation within a few days, and when I pitch into a new wort, I'll decant off and use the yeast. I hope, and ask your opinion, will this one quart jar be adequate for a 5G lager where big starters are required?

 

[JONNYROTTEN]

I use mostly us05 and almost always use a slurry.I used to use the calculators.But after a very short time I ended up more yeast then I knew what to do with.I started dumping a full mason jar just to burn it up.So that's around 500 ML.Probably triple the suggested amount.I've come to the conclusion its not worth worrying about overpitching.Underpitching is far more of a concern.Most of my beers are around 1.055 to 1.068.I never wash either,I just swirl it up and dump.

 

[WarEagleBrewer]

I use mostly us05 and almost always use a slurry.I used to use the calculators.But after a very short time I ended up more yeast then I knew what to do with.I started dumping a full mason jar just to burn it up.So that's around 500 ML.Probably triple the suggested amount.I've come to the conclusion its not worth worrying about overpitching.Underpitching is far more of a concern.Most of my beers are around 1.055 to 1.068.I never wash either,I just swirl it up and dump.

So, just to understand...after you rack the beer off the slurry, you swirl what's left, and pour it into a sanitized container(s)? Are you using pint or quart jars? So then when you re-pitch, do you just swirl again and pitch it in or do you make a starter?

 

[Morrey]

I use mostly us05 and almost always use a slurry.I used to use the calculators.But after a very short time I ended up more yeast then I knew what to do with.I started dumping a full mason jar just to burn it up.So that's around 500 ML.Probably triple the suggested amount.I've come to the conclusion its not worth worrying about overpitching.Underpitching is far more of a concern.Most of my beers are around 1.055 to 1.068.I never wash either,I just swirl it up and dump.

And I think that Pilsners are far safer to "overpitch" since underpitched stressed yeast can throw some off flavors in a beer like this. And since there is no where to hide as the saying goes with a light and moderately hopped lagers, just pitch the whole darn jar and call it a good day! At least that is what I'm going to try next.

 

[emcfarden]

I put my slurry in little 8 oz clear mason jars. I find that using one mason jar of slurry is good for an average gravity beer, and if the gravity is higher or the slurry is older I may pitch two jars. On my last brew I made a starter for the slurry and pitched at high krausen, my blow off was going crazy the next morning.

 

[Morrey]

So, just to understand...after you rack the beer off the slurry, you swirl what's left, and pour it into a sanitized container(s)? Are you using pint or quart jars? So then when you re-pitch, do you just swirl again and pitch it in or do you make a starter?

Here is my goal so take this from a guy who has ONLY used fresh yeasts and made starters:

Swirl slurry and save two 1 quart Mason jars or 1/2 gallon of slurry total. When I do my water volume calculations, I allow for 1/2 gallon of slurry to be left in the fermenter. I rack into 5G soda kegs, so I am pretty accurate with this slurry volume. Refrigerate and the slurry will separate with yeast cake on the bottom. When ready to pitch my next brew, I'll decant off most of the clear liquid (old beer) and leave the yeast cake on the bottom. I don't plan to make a starter, so I'll simply pitch the jar's worth of yeast into the new wort. I expect after separation, to have at least half of the quart to be yeast, so I'll be pitching a pint or 500ml of yeast. I am doing a Pilsner with this harvest, so its always good to have plenty of yeast to pitch. Over pitch is good...under pitch is bad.

With the price of liquid yeast, the time and trouble to make a starter, it simply makes sense (and cents) to harvest yeast. Slurry seems to be the most simple and easy way to do this harvest without all the fuss and muss of washings, even tho washing has advantages.

 

[JONNYROTTEN]

So, just to understand...after you rack the beer off the slurry, you swirl what's left, and pour it into a sanitized container(s)? Are you using pint or quart jars? So then when you re-pitch, do you just swirl again and pitch it in or do you make a starter?

Its a super easy process:
After racking theres usually around a pint or two of beer left in fermenter.Swirl that around till it mixes with the yeast cake.It will kind of get like quicksand.its now a slurry.Dump that into a mason jar and your done.Stick in the fridge till your next brew day.I boiled the mason jars the first time I used them to sanitize and was like forget this.Now I just rinse with water and spray with starsan before dumping in the slurry.Never had an issue.Clean them right after you dump out the yeast or they get crusty.
DONT CRANK THE JAR TOP DOWN!!! They build up pressure and its nearly impossible to open.Snug the lid and then back it off a little.Ive had to throw away a few full jars I couldn't get open.
If you have a Target near you they have a 9 pack of mason jars for $10 that work perfect.
I Never make a starter.Just swirl and dump.take them out of the fridge at the beginning of your brew day to get to room temp before dumping.

 

[Mainer]

Your best bet is probably to run a healthy-sized starter (~1.5 L) off a relatively-small slurry a few days before brewing. That way the yeast will multiply up to a healthy count before you pitch.

And I say that as a brewer who's super-lazy and often doesn't bother with starters.

 

[bucketnative]

Unless we had very specific and expensive lab equipment, how do we really know the vitality and yeast cell volume

Actually, that's not entirely true. With a volumetric pipette, sterile water, sterile test tubes, and some sterile wort-agar plates, you could arrive at a population of the yeast slurry.

Pipette 1 mL of yeast slurry into 9 mL sterile water. Swirl to mix well. Then make 1:10 serial dilutions from the original tube (using new, sterile pipette tips at each transfer) into tubes of sterile water. Plate 1 mL from each serial dilution on individual plates (you can use spread plate or pour plate methods). Incubate them for a few days at your fermentation temperature. Count the colonies on each plate, and multiply by the dilution factor to arrive at the population of viable cells per 1mL. Typically you use the plate the yields 30 - 300 colony forming units (CFU). This assumes that each CFU = 1 viable cell.

If you kept track of this data over time, you could arrive at an average number for your yeast harvesting procedure.

 

[seabrew8]

I've used slurry close to 20x now with zero problems. It usually ferments like a beast!

I just leave a little bit of beer in the the fermenter after i rack then i swirl it around and pour it in mason jars and place in the fridge. I used some mason jars a few weeks after i harvested it.

 

[Morrey]

I've used slurry close to 20x now with zero problems. It usually ferments like a beast!

I just leave a little bit of beer in the the fermenter after i rack then i swirl it around and pour it in mason jars and place in the fridge. I used some mason jars a few weeks after i harvested it.

Kept loosely sealed in the fridge in the mid to low 30's (F), what is a reasonable time to store the yeast without any issues?

 

[seabrew8]

Kept loosely sealed in the fridge in the mid to low 30's (F), what is a reasonable time to store the yeast without any issues?

Not sure, the sticky above has a lot of discussion on that subject. My guess is at least a month. Yeast is a lot more robust then a lot of folks realize IMHO. Treat it properly but its not a helpless baby.

You can get 3-4 bottles out of one batch so you have a lot of yeast to work with. It doesn't hurt to have a pack of yeast lying around in case something is wrong with the slurry.

 

[JONNYROTTEN]

Kept loosely sealed in the fridge in the mid to low 30's (F), what is a reasonable time to store the yeast without any issues?

Mine usually get used in about 2 months or under.I used one once that had to be around 8 months old or more.worked fine.Like others have stated I think yeast is stronger than we think.I remember hearing once they found a sunken ship from the 1800"s and there was beer onboard.They said the yeast was still viable.If it will last a 100 years in the ocean it'll last in a sanitized jar in your fridge.

 

[JJack887]

And how much of this slurry are you pitching? Just trying to get a comfortable estimate so I don't underpitch!

 

[JJack887]

Also, I kept mine in a Ball jar. I read that tightly-sealed containers may explode from residual fermentation, but the "beer" on top of my yeast is hyper-diluted. Like I said, triple-washed.