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Jun 08, 2022 View:

Yeast harvesting

Long story short,  newbie DSP orders yeast from big,  well known producer.  Newbie didn't ask for,  or receive,  a price list beforehand and orders a very expensive liquid yeast.  In order to make this purchase somewhat financially responsible,  newbie will need to harvest yeast to get 5 or 6 fermentations out of each package. 

The first fermentation we tried with the harvested yeast is going very slowly.  Only down 2 brix since we pitched Saturday.  Another fermentation we started last evening hasn't started yet. 

Any good resource out there that can help me figure out how to salvage some of the yeast costs? 


Sugar/molasses wash or grain wash? Are you doing clear wash or fermenting on the grain? What is your cook, mash or wash prep process like?


Tom, all grain (corn, wheat and rye). We do everything on the grain.  I do a hi temp cook on my corn (180 degrees) and cook the rye at 150 degrees.  Crash cool the corn mash to 150 or so and add Distillers malt.  After conversion we run through heat exchanger to reach pitching Temps  (around 75 degrees). The first generation of the liquid yeast worked great. 


How are you harvesting/re-pitching now? I will admit my experience with this is limited to a brewery setup. The information I am providing is from my limited research into re-pitching for a similar process.

The biggest challenge from trying to harvest and re-pitch yeast from that setup, will be getting a good amount of healthy yeast. Being on the grain, makes it difficult as the yeast and the grain will typically settle together, so if you re-pitch that slurry you are going to be pitching other debris and other bacterial contaminants with the yeast, which will likely out compete the original yeast the second time around. Unlike in a brewing setup where the boil would kill most or all  of the bacteria, the traditional on-the-grain process you are doing is essentially pitching lacto with your malt addition.  So by the end of the fermentation bacteria counts will be higher, and yeast will be worn out from fermentation.

If you still have the original mash, it could be possible to add O2 and try to get the yeast cell count up and use it as a 'starter' for another mash, however the bacterial counts are likely high, so competition is a major factor.  It does seem unlikely though. 

Another hope is to look into yeast washing. Some homebrew forums have info on this, it could be possible to scale up depending on how big your operation is.


Instead of trying to harvest spent, beat-up yeast, propagate from some of the fresh stuff.  It's early for me and my caffeine hasn't kicked in yet, but you can google "propagating yeast culture" and come up with a lot of good information.  Good luck!


Unless you're  bringing your mash to a boil before innoculating you're going to harvest a substantial quantity of wild yeasts with the pitched strain.  If you really want to harvest yeast you'll need to make a starter from sterile wort (I make starter from about 1040) and feed / aerate to bulk up cell count. Even then you'll need to consider if the time and cost of wort will be worth it.


Trying to harvest yeast from a prior batch with an on the grain mash seems like a futile effort.  Ordering some dried malt extract and creating starters will stretch out your yeast and get more bang for the buck.  Or just write it off as a lesson learned and find a more suitable yeast for your next order!

Reply:26 minutes ago, HedgeBird said:

All fairly good answers , Tom worked for me and he noticed a lot. And y'all ever get by his place stop now. I will tell you, it's not a boil you need anything like that you need a yeast fermenter a good. Varying flasks with air locks heating stir plate, lot of dme or a small tun for worts , plates ,and a good yeast jug. I sell the jugs and can consult on the issues. I also sell nutrients and vitally lacto be gone . You want lacto for a while then kill it. It seems complicated but not at all. Contact me and I can help .