Adding boiling wort on previous batches yeast sediments

Question

I've been using kegs as fermentors and 'no chill' vessels.

With pressurized fermentation I'm getting so much less sediment and krausen, and actually I purge the yeast before and after transfer, so ending with not so much thing inside the kegs.

I've seen people using yeast nutrients or baker's yeast on the boil to help fermentation, so, I was thinking:

if I let my fermentors waiting pressurized and then fill it again with another boiling wort, what I will get?

How yeast trub, break material and krausen things left by a previous batch could act in a new batch?

My surmise is that the boiling wort will help dissolving krausen, kill every yeast cell inside the keg, and this material will easy fall down until the end of fermentation and maybe my fermentation will be more "healthy" with all this nutrients. In the bargain, the cleaning of a fermentor could be skiped.

What you guys think? It's worth the effort on trying this aproach or its just a badtrip inside my head? Thanks!

Answer 1

You're right that dead yeast is a good nutrient for live yeast. The growth medium used for yeast in the lab is YE (yeast extract) plus some sugar.

This plan will probably provide some nutrition to the yeast, and work out OK for a few batches, but I think that problems will crop up.

1. You won't actually make yeast extract. Yeast extract is made inducing 'autolysis' in the yeast - think of it as yeast suicide by self digestion (tl;dr here and here). Your boiling wort will simply cook the yeast, locking most of the nutrients inside.

2. Protein build up: yeast don't eat proteins, they don't even secrete enzymes to break them down, they just absorb amino acids that they find in the wort/must/rotting apple. So all the barley derived proteins that go into your corny will stay there, until... who knows. Big chunks floating the beer?

3. Biology doesn't miss an opportunity. Boiling is not the same as sterilization. Sooner or later something that makes nice tough spores is going to get into the corny and start eating all that yeast and protein, and your wort. That will probably smell horrible when you need to clean it out.

Maybe the best thing is to embrace #3, chill the wort, and throw some brett & lacto in there to start a sour project.