Brewers waste yeast in thermal compost

Hello Permies World!
I'm going to start building my own thermal compost following Ingham, Lawton, etc. I have horse manure nearby, and will be using it, but I also have been offered both yeast and grain waste from a small brewer. I have found research that supports adding the waste grain, but nothing about yeast. I know brewers yeast, a fungus, make alcohol, which I presume would kill other microorganisms. If the yeast are dead, is it safe as a source of N? Is it even high in N? I don't want to add it in until I know its value other than as animal feed and what it could do to compost. Thanks in advance

Hi James and welcome to Permies.

I may be misconstruing your concern, but it seems like you're concerned that the yeast may continue to produce alcohol, which may harm other micros.  If so, don't worry.  The yeast needs sugar to make alcohol.  What you'll get from the brewers is spent mash grain, which will have about 10-15% of the original sugars still left, as well as the yeast.  The yeast won't be an issue in the compost and it will contribute to the compost.  While it's been a long time since I biologized in school, I think that the microorganisms in the compost may be able to readily use the nutrients from the dead yeast.  I wouldn't hesitate to add it to the pile.

One caveat from a homebrewer is that spent grains smell worse than just about anything else I've experienced, including a sewage treatment plant, so you'll want to make sure it's well covered and aerated.  Spent grains will bring flies like nobody's business, but you should be fine if covered enough.  The pile may stink when turned, though.

Good luck.

edit:  FYI, brewers yeast is used in many animal feeds for the B complex vitamins, so it's a staple in today's agricultural feed.

Thank you very much Timothy. My hope is I discover from my friend the brewer the yeast is deceased, but if it's not, I think I can rely on your assessment. Healthy compost will already be competing for those sugars. I'm speaking with a thermal composter at his farm this morning, and I'll be happy to share whatever I can learn. Thanks again!

No worries, James. If the yeast is wet, there will be live yeast, but it won't be a factor as they'll soon die off or go dormant.  Around here, most brewers dry the grain and yeast to dispose of it, though that may be just to reduce the transportation costs.  I knew one guy who got paid by a micro brewer to take his spent mash, but that was a while ago.  Regardless, it may be worth the brewer's while to pay for the transportation to you.  I'm not sure what your arrangement is, but that's what I'd try for, though I'd probably pick it up if I had the right composting set-up.

Let us know how it goes.

Hi James, I've been composting SBG for years. It is wet and dense, and needs good mixing with bulky brown materials to keep it from going anaerobic. Also high in phosphorous, so keep an eye on soil tests if you are composting lots of SBG.

The brewery that I deal with takes the yeast trub from a prior batch and adds it to the hot mash (after the wort is drawn off) to kill the yeast. The mash acts as a filter bed to allow the liquid in the trub to drain away.

A couple of related threads:
spent brewing grains uses
brewery mash business case

I operate a small commercial brewery and have a little land for gardening. Most of my spent grain goes to a farm to feed livestock, while I always take a few buckets of spent grain home to turbo-charge the compost. It breaks down so hot!! We mix it thoroughly with horse stable straw to promote aeration and increase carbon content - I understand a smelly heap is carbon deficient and sheds nitrogen as stinky ammonia. The heap quickly hits 70°c+ and requires turning every second day.
On the topic of yeast: it dies at temps over 55°c - otherwise will consume a lot of oxygen of it's left to autolyse (it'll eat itself before touching most of what's in your compost heap - I wouldn't rely on the yeast strains commonly found in the brewery to process anything but simple sugars). If you're cold-composting I'd heat treat the yeast before mixing it thoroughly through the heap.