Dumping fresh wort onto the yeast cake

[JohanTheMighty]

Good afternoon, I ended up here after doing a google search about reusing yeast. As you can well imagine, one of the search results led me to a thread from this specific forum and in that thread everyone was saying that if the timing is right you can just dump fresh wort right onto the old yeast cake. My question is whether the type of beer that was just emptied from the carboy would impart off flavors into the new wort that was just dumped on top of it.

So, if I just emptied an imperial ipa, using Safale-05 yeast, from my carboy, and my next batch was going to be an imperial bourbon barrel stout that calls for the same yeast strain, would I be better off washing the yeast and saving it for later use, or will remaining flavors left over from the imperial ipa be "scrubbed out" during the imperial bbs fermentation? Though everyone on that thread (an admittedly old thread dating back to 2009, lol) was promoting the idea of dumping right onto the freshly used yeast cake, the subject regarding how the leftovers from the previous beer might affect the new one was not discussed.

 

[jtratcliff]

You probably don't need the entire yeast cake... maybe 1/4 to 1/5 of it or so... I try to usually go from less hoppy to hoppy, or from light to dark when directly using the old yeast cake.... But I don't know that using 1/5 of the cake will leave enough hop debris and old beer to affect the outcome. I wouldn't do a cream ale or a pilsner after an IIPA, but a stout might be just fine....

You can easily do a quick rinse... swirl up the yeast cake with a bit of water, pour off into 4-5 1-pint mason jars. Let sit for 20 minutes or so. Pour off the spent beer and debris layer from 1 jar and pitch what's left. That should get rid of quite of bit of the potential problem. Plus you now have 3-4 extra jars to use later...

But the whole cake is probably a pretty big over-pitch. At the very least scoop some out.

 

[JDXX1971]

I just did it. Brewed a 1.063 porter last weekend fermented with a pack of Nottingham sprinkled on the top. Today I brewed an imperial version of the same beer, 1.084 transferred last weeks brew to a keg (done enough at 1.017) and dumped the new brew right on top of the yeast cake and left overs. three hours later and it has taken off like a rocket.

Giant over pitch? I'm sure it is, but I am not too worried about it. I will report back here if it anything seems off.

 

[JohanTheMighty]

Thank you both for the input. I figured that there were variables to consider that were not being discussed, including what beer to follow the previously finished one, and pitch rates. Thanks for helping to clear that up for me.

 

[JohanTheMighty]

I just did it. Brewed a 1.063 porter last weekend fermented with a pack of Nottingham sprinkled on the top. Today I brewed an imperial version of the same beer, 1.084 transferred last weeks brew to a keg (done enough at 1.017) and dumped the new brew right on top of the yeast cake and left overs. three hours later and it has taken off like a rocket.

Giant over pitch? I'm sure it is, but I am not too worried about it. I will report back here if it anything seems off.

Please do.

 

[Jayjay1976]

I don't like the idea of pitching fresh wort in to a dirty fermenter. Just save some of the cake and pitch that into a clean, sanitized fermenter filled with the new batch. Definitely save the rest in jars for future batches to save some money like @jtratcliff suggested. With careful storage and rotating the styles you brew, you could be buying each strain only once per year. If I see some jars are getting older than 3-4 months I'll brew something to use those up and harvest the fresh yeast cake when it's ready to replenish my supply. I normally keep 3 jars each of 4-5 strains on hand in little 4oz mason jars and build starters from them before brew day.

 

[Amadeo38]

Agree with everyone else here. Including not going from hoppy to non-hoppy, or dark to light, when re-using a yeast cake without washing.

One thing to add - boil good water and let it cool down before adding it to the cake if you’re going to swirl and decant into mason jars to wash. Also, I’ve only ever used mason jars that I boiled for 10-15 minutes before hand. One way to knock out two birds with one stone is to boil four mason jars in a big stock pot of water, lids and all, fully immersed. After 10-15’ in the boil, cut the heat and remove with boiled metal tongs, FULL with water. Place the lids on and set them aside to cool to the temp of your yeast cake. Then pour them into the fermentor on top of the yeast cake. Swirl, and pour back into the sterilized jars. Put in fridge for a bit until you start to see separation. Pour off the junk, and enjoy the rest. There’s a great YouTube video describing this procedure if you search for “yeast washing”

 

[JDXX1971]

I did feel a little dirty after dumping into that cruddy looking fermentor.

I was brewing quick and dirty though. Inside on the stove top with an element in the kettle too. No re circulation and no controller, I left everything in the shed and just brewed some beer.

I do have a keg fermentor almost finished with a bottom dump and Jaybirds canning jar yeast harvester adapter. I plan to harvest and save yeast like Jayjay describes and I like Amadeo38's idea of just boiling the jars and using that water to dump in the fermentor.

As far as this batch goes though hopefully everything will turn out ok. It did take off like a rocket but it is in my sad empty keezer for temp control which I think will help. I was being lazy, I admit it. I probably wont do it again, unless the beer turns out killer.

 

[deadwolfbones]

I'm planning on doing this with a Patersbier (Belgian single) followed by a Belgian quad/dark strong, both with WLP530 and Styrian Celeja hops.

 

[eltorrente]

I've done it a few times before and never had issues. Beers always came out great.

 

[Jayjay1976]

Pitching fresh wort into a dirty fermenter is a bit like breaking the bird's neck twice to the same centerfold.
It just isn't done. Not in polite society, anyway.

 

[eadavis80]

I dumped onto a cake one time and I'm not sure I'll do it again. For whatever reason the beer stalled out at 1.030 even though I didn't mash at a high temp. Maybe there was something else wrong, but the attenuation was sad which seems odd given I would have had a zillion yeast in there to eat the sugar. Hopefully your batch turns out better than mine.

 

[RM-MN]

Pitching fresh wort into a dirty fermenter is a bit like breaking the bird's neck twice to the same centerfold.
It just isn't done. Not in polite society, anyway.

How dirty is your fermenter? I only allow beer in mine. Krausen stuck to the side is only krausen and your next batch will produce more.

Pitching onto a whole yeast cake can be done but it tends to lead to an explosive fermentation in which proper fermentation temperature is hard to control and often leads to over attenuation. Reusing the yeast cake from an imperial IPA may not be the best because the yeast will be stressed from the high alcohol content.

 

[madscientist451]

Pitching fresh wort into a dirty fermenter is a bit like breaking the bird's neck twice to the same centerfold.
It just isn't done. Not in polite society, anyway.

No polite society anywhere in sight around here, so frequently I re-use the same yeast cake AND fermenter, usually with cider but sometimes with beer. If the fermenter has a large amount of high krausen crap sticking to the sides I usually clean it before re-use.
I stopped washing yeast years ago, figuring the extra handling was just another chance for contamination.
Just dump the yeast slurry into a sanitized mason jar and place in the fridge if you want to save it.
Another assault on polite society norms is re-filling a keg without disassembling and cleaning everything. if the beer goes down fast, I just rinse it out re-fill it and then clean everything after the second use.
Disgusting and uncouth, I know, but it doesn't seem to hurt anything.

 

[jack13]

Agree with everyone else here. Including not going from hoppy to non-hoppy, or dark to light, when re-using a yeast cake without washing.

One thing to add - boil good water and let it cool down before adding it to the cake if you’re going to swirl and decant into mason jars to wash. Also, I’ve only ever used mason jars that I boiled for 10-15 minutes before hand. One way to knock out two birds with one stone is to boil four mason jars in a big stock pot of water, lids and all, fully immersed. After 10-15’ in the boil, cut the heat and remove with boiled metal tongs, FULL with water. Place the lids on and set them aside to cool to the temp of your yeast cake. Then pour them into the fermentor on top of the yeast cake. Swirl, and pour back into the sterilized jars. Put in fridge for a bit until you start to see separation. Pour off the junk, and enjoy the rest. There’s a great YouTube video describing this procedure if you search for “yeast washing”

Ha! Precisely what I do! Actually, I have a big lobster pot so I can do 8 mason jars at a time and just keep them on hand.