We are trying to develop a method to dry spent grains with a small DIY solar dryer. When we pick up the spent grain it is get too much volume for our dryer and then how to store it. Our drying process is very small and slow. We do not have the ability to freeze the spent grain.

We have developed and plan to use a 5-gal bucket system in which the lid pushes all the air out of the bucket. The lid has an airlock. We plan to put the spent grain in these 5-gal buckets with water, push the air out, put in the airlock and store them until the dryers are free to process the spent grain.

Our questions are: 1. Will this work?
2. Should we mix yeast or sugar into the buckets to keep them from spoiling?

We are not brewers, so this is all new to us. Thanks for any input

  • If you cannot use a freezer, can you use a refrigerator?
    – Philippe
    Commented Mar 30, 2018 at 12:52

1 Answer 1


Usually it will sour within hours of after being mashed unless dried or pasturized right away.

The only way I know to "preserve" it would be to boil it to kill the lactobacilla. Then sealing should preserve it awhile so it can be dried at a later time. But may not be worth it financially.

I'm not sure what your using it for.
Most that use it for feed just serve it up damp asap, animals generally know once lacto has turned it sour and don't touch it.

1. Water filled no, this will not work. The grain is already "infected", filling with water and using an air-lock is futile.

2. Adding sugar and yeast This also won't work as the grain already has lactobacilla, and it would consume the sugars before yeast could get started to make preservative alcohol.

  • Agree, it gets funky very quick. I once tried drying some in an oven during the wort cooling, so about two hours after mashing but the resulting granola bars had that sour tanginess. But how do professional breweries do this? A lot of them claim they reuse it to feed animals and it wouldn't be very economical/ecological to dry them…
    – JesseB1234
    Commented Mar 30, 2018 at 11:31
  • @JesseB1234 most pro breweries have daily pick ups from local farmers and the spent grain goes straight to the stock animals. The HEBS system among others use a grain press, so the grain is almost dry "damp" when disposed of. Commented Mar 30, 2018 at 12:33
  • Using a press to get most water out is a good idea, it could be part of the solution.
    – Philippe
    Commented Mar 30, 2018 at 12:54
  • 4.8g of potassium metabisulphite in 5-gal of grain should give 150ppm of sulphur dioxide. This will inhibit most spoilage organisms for at least 24 hours. 150ppm SO2 is level safe for human consumption. Commented Apr 1, 2018 at 7:19
  • @KevinSharp potassium metabisulfite would just force the lacto to be anaerobic and activate pathways to produce only acid. Commented Apr 1, 2018 at 13:03

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.