Re-pitching yeast slurry

[LovesIPA]

I thought you could do this. Maybe I did it wrong?

I harvested 3-4 jars of yeast slurry from a prior batch about a week before brewing my last batch. They were in the fridge the whole time.

Two days ago I brewed and pitched about 300 ml of slurry which should be plenty for a 5 gallon batch. I shook it up and when I checked on it 24 hours later, the airlock was not moving. There was no krausen at all and no activity.

I know what everyone says - airlock activity is not an indication of fermentation. However, every other batch I've brewed has always started fermenting in that time frame. This batch was in a sealed glass carboy - not a bucket - so there was no air escaping from a loose bucket lid.

Yesterday I decided that I'd better pitch some dry yeast I had on hand rather than wait around long enough for an infection to develop.

I also tried pitching slurry once before. It did start fermenting after considerable lag (< 24 hours), but it was verrrrrrrrry slow. It finally finished but I was a little worried. That slurry had only been in the fridge for a day or so.

So can you not just re-pitch yeast slurry? Is there more to it than that?

 

[No1ukno]

I just pitched 100 ml slurry that's two weeks old with a half liter startes and she was very aggresive within couple hours and at fg within 5 days. Maybe you shoulda waited or maybe something happend when you were washing.

 

[catdaddy66]

I believe its best to use slurries in a starter due to their dormant state (cold and minimal oxygen) after being rinsed. Warm them up gradually and put them in some dissolved DME (500-1000 ml) and let them get busy! then after a day or two they should have multiplied enough to do the job you need.

I think rinsed yeast have insufficient numbers without being given time to reproduce in a starter. A classic example of under pitching.

 

[LovesIPA]

Yeah... I skipped the starter. Will have to remember it's not an optional step in the future.

Do you harvest yeast from higher alcohol beers without any ill effects?

 

[Cyclman]

Higher alcohol beers will stress the yeast, so it will reduce the number of times that yeast can be re-used without issues. You can always split your starter, and use 1/2 the yeast in a new starter for the high OG beer, then save the rest for a low gravity and re-use that. Always use a calculator to estimate the proper yeast amount.

 

[BigFloyd]

So can you not just re-pitch yeast slurry? Is there more to it than that?

Lots of folks, including me, re-pitch slurry (both rinsed or un-rinsed depending on the situation) with zero issues.

I usually over-pitch by about 10-20% (above the Mr. Malty recommendation). If it's pretty fresh and I have enough of it, I'll not do a starter. Otherwise, I do.

 

[eric19312]

I repitch yeast slurry all the time following mr malty volumes (maybe a bit more). No starters ever. I use only US-05 yeast. I only harvest yeast from batches under 1.055 OG, moderately hopped, and if dry hoping a batch I want to harvest, I use a secondary and dry hop in there...harvest from primary. Normally I'd not bother with a secondary on a moderate or lower gravity beer.

I also only use slurry when the previous batch comes in clean.
That means there is usually a month lag or more between harvesting slurry and using the harvested slurry.

 

[Doed]

Alcohol content plays a role in yeast viability. Check out Woodlandbrew's blog about it here -> link

I pitched two pints of slurry from a wheat beer two weeks after collection and it worked like a champ. All I did was boiled my two pint mason jars, swirled the trub after racking the wheat beer, and pouring the trub into the pint jars. I sealed the jars and put them into the fridge. On the next beer, I let the pint jars warm to room temperature and poured the slurry through a sanitized strainer to catch as much hops gunk as possible.