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How much beer can the slurry make?

Curious to know without a lab or means to know cell-count how much beer a fresh slurry from a 6.5 gal carboy could inoculate. If I had to guess I would say a lot…maybe even enough for a 5 barrel brewpub system? Does a higher OG recipe produce a much larger slurry? If so would that mean that a 1070 wort might produce twice the slurry as a 1035 wort?

A typical average gravity fermentation may result in enough yeast to brew 4 more average gravity beers if used immediately. Not all of what you see at the bottom of the fermentor is yeast. Some of this is coagulated proteins and break material.
The yeast propagated in a 1.070 wort will not be twice that of a 1.035 wort. May be the same amount. You would not harvest yeast from a 1.070 OG beer to reuse. The yeast is to stressed. Results of a fermentation with this yeast would be unpredictable.
I estimate one billion cells per milliliter in harvested yeast that is clean. I would rather be conservative here and over pitch than suffer the consequences of under pitching.

you can use mrmalty.com to determine the viability and proper pitch for your harvested slurry.

I just re-used slurry a few days ago. In this case I racked the beer off into a keg, poured out about 2/3 of the cake into a mason jar to save and then just poured my newly brewed and cooled wort into the carboy with the remaining 1/3 of the cake. It was fermenting within hours.

I saved about 1200ml of slurry and estimate that I used about 600 ml with the new wort. Based on the most conservative settings in mrmalty for thickness of slurry and percent of yeast I figured I needed 562ml to get 226 billion cells for my 1.062 wort.

I just harvested and reused slurry from a 1.082 to use in a 1.076 no problem. For a 20 gallon batch I tried splitting half just dumping slurry from a carboy into the fresh wort in clean carboy(s). The other half I used slurry harvested from my conical, saved in a mason jar then used in a small “starter batch” to add back into the conical after it was emptied and cleaned.

Both fermented out nicely. The only difference I could see is that the wort dumped right in took much longer to settle and clear with more trub in the bottom. FG of all was the same 1.010. All of it was oxygenated with an aquarium pump and sugar added (Belgian Ale) to lower the gravity and give it “drinkability”. The first batch has caused some early nights and morning headaches :roll:

[quote=“dannyboy58”]you can use mrmalty.com to determine the viability and proper pitch for your harvested slurry.

I just re-used slurry a few days ago. In this case I racked the beer off into a keg, poured out about 2/3 of the cake into a mason jar to save and then just poured my newly brewed and cooled wort into the carboy with the remaining 1/3 of the cake. It was fermenting within hours.

I saved about 1200ml of slurry and estimate that I used about 600 ml with the new wort. Based on the most conservative settings in mrmalty for thickness of slurry and percent of yeast I figured I needed 562ml to get 226 billion cells for my 1.062 wort.[/quote]
How many yeast cells do you estimate in a ml of slurry? Do you have visible hop debris in the slurry you pitch?

Mr. Malty is an excellent source! I’ve read many posts from people who simply rack their next brew directly onto their last brew’s yeast cake. I’ve also read many posts about yeast washing, both for and against. Here is a nice, illustrated post on yeast washing that I found helpful:

There are also many videos on YouTube.

One thing I read a lot while researching the subject is that you should harvest yeast from less hoppy beers to use on more hoppy beers later, versus the other way around. I’ve done the former, but not the latter. I’ve also quit harvesting altogether, as that yields way more yeast than I want to keep on hand due to space limitations. I’ve instead taken to making an extra big starter and saving a portion of the starter for a future batch. It yields one jar of yeast to save versus four, increases the number of strains I can keep on hand without taking up valuable space in my only refrigerator, and gives me neutral, hop-free yeast…

I’ve heard and read that too…but have to say that in 40+ years of homebrewing (and 30 years of using and repitching “wet” yeast) that using repitched yeast from a hoppy brew has never created any problems with excessive carryover of bitterness. I’ve successfully made many batches of Mild Ale (in the modern, low gravity/low bitterness sense) using the yeast retrieved from fermentation of a very highly hopped / high gravity Burton Ale. Doing so never once yielded unexpected results.

Research via personal experimentation is encouraged…as a result (at least occasionally) it can become quite evident that conventional accepted wisdom is not always the last word.

[quote=“flars”][quote=“dannyboy58”]you can use mrmalty.com to determine the viability and proper pitch for your harvested slurry.

I just re-used slurry a few days ago. In this case I racked the beer off into a keg, poured out about 2/3 of the cake into a mason jar to save and then just poured my newly brewed and cooled wort into the carboy with the remaining 1/3 of the cake. It was fermenting within hours.

I saved about 1200ml of slurry and estimate that I used about 600 ml with the new wort. Based on the most conservative settings in mrmalty for thickness of slurry and percent of yeast I figured I needed 562ml to get 226 billion cells for my 1.062 wort.[/quote]
How many yeast cells do you estimate in a ml of slurry? Do you have visible hop debris in the slurry you pitch?[/quote]

I use the most conservative settings in mrmalty which is 1 billion yeast cells per ml, and 25% non yeast materials in the slurry. I figure this is erring on the high side when I pitch. Whether or not there is visible hop debris depends on the beer but there’s usually not a lot since I bag hops in the kettle and when I dry hop as well as pouring the wort through a double mesh strainer into the fermenter.

I totally agree. As I always say, “‘Conventional Wisdom’ is usually neither…”

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