Recycled yeast

[beninak]

I'm trying to reduce my carbon footprint and battle global warming rotest:, so I just made my first attempt at re-using a yeast cake for my beer. ;D

The fermentation seems to be going great but I'm interested to taste the results. A quick question: when reusing the yeast on a new batch of wort, should it be more or less the same recipe or can you mix it up without ruining the flavor too much?

For example: I used the Wyeast Belgian Strong ale yeast with a wort that had about 30% wheat fermentable in it. Now I try to re-use that same yeast with a wort that is more intended to be a Belgian pale ale. Will it work or will I get a lot of extra fruity esters and cloudiness because the yeast was used with wheat before?

Also, say I use Wyeast 1056 American Ale yeast to make a Pale Ale, then re-use the yeast to ferment out a low-alchohol mead. Will that work?

 

[wildaho]

Hey Ben,

I re-use my yeast cakes all the time. There is only one major rule to follow: always make the second batch the same or better yet, make a bigger beer than the first. In other words, you brew a 5% beer the first time. When you re-use the cake, go for a 7%-12% beer.

If you had a normal fermentation without excessive stress, there shouldn't be any off flavors, just the flavors imparted by the yeast normally. The only stories I've heard of off flavors are when the cake started out from a big beer and was then used to make a smaller beer.

Re-using the yeast cake is the best method I've found for doing a barleywine. I'll start by making a 7% or so pale or IPA and then pitch a high gravity wort (1.120~)on the cake. Re-using the cake always gets me the attenuation I want where a direct pitch of fresh yeast (even as a starter) won't.

good luck!
Wade

 

[akueck]

Just to add to that, the rule of thumb for flavors is also to go bigger on the second pitch. So the second beer should be as hoppy or more than the first, etc.

The danger with funny off-flavors (aside from trub) is when you severely overpitch. Using the whole yeast cake will probably be more yeast than you need regardless, but by dumping a higher gravity wort onto it you minimize the difference between ideal yeast count and your actual count.

Another thing to consider when pitching on a yeast cake is the amount of esters/phenolics you want in the beer. Many/most of these are produced during the lag phase, which you'll skip by using the cake. So if you want some characteristic yeast flavors, you might miss out on them.

I've repitched on a couple yeast cakes, but more recently I've been collecting the yeast from the bottom of the carboy. I add some preboiled water, swish everything around, and dump the liquid into a pitcher. The trub, dead yeast, overly tired yeast, etc settles out first, then I collect the slurry at the top. This can either be pitched as is or stored for a week or so in the refrigerator. This way I'm not recycling the trub from the first batch and also reducing the cell count to normal levels. Also, I can vary my pitch rate by using more or less of the slurry.

 

[yabodie]

Yup, start small both beer and hop bill wise and don't pitch on the entire cake, assuming sanitation is good...