After a 3 year hiatus to take care of an aging parent, I am back to my brewing ways. One of the ongoing projects I left behind was a library of stored yeast kept in the freezer section of my beer fridge. While I was away I checked in with my neighbors in case there was a power failure, and to my knowledge there wasn't anything more than an hour or two. The yeast samples were stored in a glycerin solution in sealed test tubes and stored in an insulated box.
Yeah it could have been thicker, but I had pounds of homegrown hops vacuum sealed in there as well. The freezer section was also frost free, so that worked against me too. I still was able to bring back viable yeast after 2 years, but after 5, it seems my luck had run out.
One thing I noticed was a phase separation between the water and the glycerin, with the ice floating over the glycerin as seen in the right photo. The yeast settled into a pill sized deposit at the bottom of the vial, and was dark in color. I had 30 or 40 vials, and this was typical.
I have attempted to revive the yeast with 300 ml of extract at about 1.030 on a stir plate, but all I have after 2 days is basically dark colored starter with very little evidence of yeast growth. I guess I need to rebuild my library, and use or regrow the samples every couple of years. My brother is a biochemist tells me how they do it in their lab, but I can't afford to keep yeast samples on liquid nitrogen.
Yeah it could have been thicker, but I had pounds of homegrown hops vacuum sealed in there as well. The freezer section was also frost free, so that worked against me too. I still was able to bring back viable yeast after 2 years, but after 5, it seems my luck had run out.
One thing I noticed was a phase separation between the water and the glycerin, with the ice floating over the glycerin as seen in the right photo. The yeast settled into a pill sized deposit at the bottom of the vial, and was dark in color. I had 30 or 40 vials, and this was typical.
I have attempted to revive the yeast with 300 ml of extract at about 1.030 on a stir plate, but all I have after 2 days is basically dark colored starter with very little evidence of yeast growth. I guess I need to rebuild my library, and use or regrow the samples every couple of years. My brother is a biochemist tells me how they do it in their lab, but I can't afford to keep yeast samples on liquid nitrogen.
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