Recent experience re-using yeast in non-sterile all grain.

[LBHD]

Hi -

TL:DR - I recycled yeast in 3 of my all grain ferments over a couple months and have not had an issue with bug takeover, and I think it could be a fairly repeatable process for everyone.

For my last 3 fermentations, I have been doing the no-cook corn method, then adding and mashing barley + other malts like Jimbo's wheated bourbon in T+T describes. So, I start with a sanitized 15 gallon BOP, then add boiling water+backset, then add the corn. The corn part gets sterilized, temp drops off to the 150s, and add barley. The barley malt is inherently populated with lactobacillus and wild yeast, but it is held at 140-150 F for several hours. Eventually, I get tired of that and stir it down until it gets to to 80f, then I pitch about 2-3 qt of yeast trub and ferment for 7-8 days on the grain, squeeze out all the liquid out I can into 2 buckets and cold crash in the fridge.

I have re-used the yeast + trub from the cold crashed distiller's beer 3 cycles now on the same recipe with no issues with infection from other bugs.

This got me thinking about the properties of all of our different microbiological friends around, and here is why I think it has been successful so far -

My BOP/fermenter has been sterilized before starting, and then gets boiling water, and stays >140 for several hours during mashing. The FDA has a chart with most bad bacteria in meat that are killed by holding meat at temps in the 140s over this time range.

bacteria-safety-01[1].jpg

I know we arent dealing with the same species here, but the lactobacilli I use in cheeses is pitched in the 110s, 120s at the max.. so long story short, I think that with this method, the ferments are starting out more "sterile" than we would normally assume.

My fermenter is not airtight, but I start sterile and use best practices, and dont stir or fiddle with unsanitized implements.

I give my yeasties a pretty good competitive advantage using backset to correct pH and putting a good 2-3-qt or so yeast cake in.

The "beer" ferments in the mid 60s using this yeast, which is too low for some other bacteria to reproduce rapidly.

I have been cold crashing for several days for the sake of minimizing yeast + trub into the fermenter and for preventing hostile takeover of mashes that I dont have time to run yet. This probably also helps prevent some late bacteria takeover?

Finally, it is winter in the South, so the wild bacteria and yeast population is probably lower than other parts of the year.
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The nice part about this is that I can get my ferments healthy and quick with little work and no additional $ in yeast. I am using ale yeast which is not cheap and would have to be stepped up with starters to pitch on 15 gallon ferments.. this one in particular is one I harvested from a bottle of beer so it has been free!

I feel like considering the points above, the risk of infection is pretty low. I also keep an eye on my ferments and would not re-pitch if I did see some sort of other colonization going on, but so far it has been fine.

Does anyone else regularly recycle yeast/trub to pitch for next fermentation?

[Red Rim]

I will reuse my yeast while making beer, and often reuse my beer yeast for my corn mash. Like you mentioned, some of the beer yeast can be spendy. Sometimes I do it just because I hate to throw things away.
I like your points on the temperatures bacteria prefer. My only infections have come from sprouted corn mash, where I was afraid to get the temperatures to high in fear of killing the amylase and often occurred at the end of the ferment cycle.

[LBHD]

I am just hoping that the luck holds out through warmer weather when there are more wild yeasts etc around - will update here every so often I guess to pass along the anecdotal data

[LBHD]

Quick update re: continuous fermentation thread.

No problems so far! Took a bit of a break during hottest part of summer to help regulate ferm temps. Yeast trub has survived several months of refrigeration and is still viable.

[BaxtersDad]

Your technique sounds impeccable. We reuse a commerical pitch (Calfiornai Ale Yeast) up to ten generations on our commerical brewery for beer. The large quantity of pitch is really critical to get the new ferment off to a fast start. Our pitching rate is 1 lb. of yeast harvested from the fermenters per bbl (31 gallons) of wort. Many of our brethren here scoff at "clean and sanitary," but anyone who has ever been around a brewery or done serious homebrewing will understand why you are successful when other threads here pop up like "Infected fermentation?"