pitching on a previous yeast cake

[croc4]

So I have read a few threads that say this works well, if the yeast cake is used shortly after the previous batch is drained.

But this leaves the trub and cold break from the previous batch as well, so is there a risk of getting off flavors by pouring a new batch of brew onto the yeast cake left in the primary of the previous batch?, (they are both brown ales, with similar recipes)

(I plan on racking a batch to secondary as I am brewing up a new batch, then just dumping the new brew into the primary without removing the yeast cake.)

opinions?, thoughts?, rants are cool too ;-)

[Jeff]

In a previous thread, I think it was Salad that said a homebrewer at the LHBS was relating a story of his carboy exploding after doing such an act. Of course I think this makes it third hand gossip, so give it a try put it in a room you don't care about and let us know about the shrapnel effect. :D

[wortchillergoal]

I did this once. After a brown, I dumped a barely wine on top of the yeast cake. I had no troubles. Since it was a big beer, I used a blow off tube so I had no exploding airlocks yet alone carboy. Everything came out fine.

[Tweek]

The only way that I could think of that a guy could get an exploding carboy is by pour hot wort into a cold glass carboy. There is nothing explosive in the trub that would cause such a reaction by itself.

[yonkersbrewer]

Since I brew at a 2.5 gallon size for space and other considerations I often have to split a kit. In those cases I always brew batch 2 atop the yeast cake of batch 1. I have had great luck with it and the fermentation is spectacular because of the huge amount of yeast present. It starts right off! In fact I noticed once that I was not able to take a OG reading because by time I cooled the wort to reading temps it had begun to bubble already in the hydrometer cylinder.

Try it - it works!

[croc4]

I am less concerned with how well it works, and more concerned with does it impart any off flavors?, you rack to secondary to get it off the trub from the primary, but when reusing the yeast cake/trub does this have a risk of increasing off flavors?

[Tweek]

dont know for sure. My guess is that it will increase the chance of off flavors. The reason you rack off the trub is because it starts to break down. It is this process that contributes the off flavors.

[bierboy]

I do it all of the time. As long as you are anal about sanitation it is a great way to stretch your dollars. There is also the benefit of having a really large starter for your wort. You will see a really fast and vigorous start. I just did a batch with Wyest Belgian Wit and it took off within 2 hours.

Two notes of caution though. Use only plastic fermenters for this technique. Frequently the lid will blow off because of all of the pressure. This is especially true of ales. You don't want a glass carboy shattering.

In addition, you do not want to drop fresh wort on the yeast cake more than 3-4 times for lagers and 5-6 times for ales. Their is an increased risk of infection the more times you do it and an increased risk of yeast mutations.

Generally, I never go more than 3 for either ales or lagers. After all, how much of one yeast strain does one want to have on hand. I like to keep a little variety in my beer stock.

[Fast_Eddy]

The only way I've ever done this is to rack onto the yeast cake in the bottom of secondary. To me it is more likely to be mostly comprised of yeast as opposed to the hops, break material, by products amalgam that is at the bottom of primary.

[BeerBelly]

I do it all of the time. As long as you are anal about sanitation it is a great way to stretch your dollars.

Bierboy
When you do this, do you make the same kind of beer several times? Or do you make different kinds of beer? I would like to do this also, but instead of 20 gallons of one kind, I would like to vary the kinds of beer. Would it be possible as long as the different kinds of beer use the same yeast?

Beer Belly

[sullydavid]

I do it with different types of beers all the time. In fact I am just about to go on a bottling binge after making three Belgians on the same cake. I think the general rule is to go from lighter to darker beers. But I have heard of other methods such as fewer IBU's to more, more IBU's to less, etc.

I have never had any issue using this method other than the batches kick of to a VERY vigorous fermentation. I have never experienced any off flavors doing this.