Expert: Keith Patton - 5/7/2011

Question
I work at a brewery that makes up to 10M litres of beer a year.   We have waste yeast (spent yeast) liquid that we pay to get rid of.   Any idea what this could be used for or who I could approach to see if someone would take it for free if it could be useful?   It is liquid - we can heat it up to kill off the yeast to make it inactive or leave it in it's active state depending on who wants it.   It just seems just a waste.  Any ideas would be appreciated.

Answer
Sammy:

Welcome to the age of high technology.  Once upon a time, brewers yeast was made into table form as a great source of amino acids. As a weight lifter, I used to pop them by the hand full back in the 70's and 80's.  Then came amino acid caps and liquids.  No longer did you need to ingest yeast and have your body break the proteins down, you could simply take the readily available pharmaceudical grade amino acids.

I worked in a lab that grew yeast as a form of protein for use in protein bars back in the 80's.  I don't know if they still use that as a source or not.  They did market the product which was kind of dry to the taste, as a horse feed.  

Does the yeast sediment contain hops?  If so that might be problematic.  I think the best bet is some kind of amimal feed.  If it could be pelletized by some process, adding a binding agent or extracting some of the liquid  to make it amenable to processing into pellets, then used as an animal feed it might be a good replacement for corn.

Corn is not the best feed for cattle as it irritates the stomach lining of their stomachs during their stay in the feed lots during the fattening up process.  This irritation, similar to irritable bowel syndrome can make them succeptibe to other infections and is why they pump them full of antibiotics and steroids, to prevent any mass outbreak of infection.

A good simple protein feed that is affordable and nutritious might be very marketable especially to the organic meat growers.

The precence of hops in the yeast sediment might be a problem though.  It might cause a discernable flavor to the meat if fed in large amounts.  I don't base this on any empirical data, just from the knowledge that hops can be discernable in your sweat and long time exposure might cause the hop oils to saturate the animals whole body.  I might be out in left field on this, lol, but tests would need to be conducted.  The bitterness of the spent hops depends on how efficient or inefficient the hop oil extraction is into the wort boil, might mitigate this.

Hope this gives you some ideas.