Zombie Yeast

A while ago I was asked an interesting question about brewing: do I culture and reuse yeast? At the time I was just starting to brew and the answer was certainly no. Why would I? Yeast wasn't too expensive and I felt much more comfortable following the recipes straight up.

I typically add dry yeast or liquid yeast that comes in a small packet or vial, which will then begin to rapidly reproduce over the coming days. However, it still takes a bit of time to hit the maximum amount of yeast. Often people create something called a starter, where they culture the yeast to a high quantity beforehand in order to kick of with a quick fermentation.

Once the fermentation has finished the yeast has no sugars left to consume; it goes dormant and sits in the fermentor until you siphon the beer out and bottle or keg. What's left at the bottom of your fermentor is giant pile of yeast, called a yeast cake which has already done its job and typically gets tossed. You can see it quite vividly at the bottom of my cider.

However, it is possible to pitch using your yeast cake, reviving it from retirement. I've always wanted to try but was waiting for the right yeast/beer combo, as the previous beer and future beer should similar styles that work well with that particular yeast strain. I was also wary of the sanitization and risk of possible infection.

But the other night I decided to finally take my chances and pitched an odd variation of an ESB (Extra Special Bitter) on top of the yeast cake from my Smoked Efficient Czech. The yeast strain, Safale 05, is a pretty standard yeast and has been used in a number of my previous brews.

I'm a bit worried about sanitization, but am not overly invested in the ESB as it was cheap and intended as a casualty of my experimentation. Luckily, I think I may be overestimating the risk of infection. And the fact that such a high quantity of yeast already exists means that it will get straight to work, hopefully overpowering anything else in its rapid sugar consumption.

Beautiful, right?

As you can see the yeast cake isn't pretty, but it gets the job done! Typically it looks much smoother/cleaner, but not this time. We shall see how this turns out.

PS: If you're trying this yourself, I forgot to mention a couple qualifications I discovered while digging around.

1. Your new brew should be a higher gravity beer (more malt & sugars) than the previous otherwise it will be considered overpitching.
2. Use a blowoff tube!
3. Don't reuse the same yeast more than ~6 times (evolution?)

Anyways, na zdravi for now!