Old Yeast Starter

[bboykin87]

I have a Mason jar of yeast I harvested over a year ago. I want to use it again but I'm unsure if it is still good. I'm thinking about making a starter with it. Am I correct to assume that if it propagates and there are no foul smells that the yeast is good to go? Thanks for any insight anyone could give.

 

[jekeane]

It's certainly possible. I have done it before. Now there is also a good chance that the yeast has changed over that time period. Could be more or less flocculant or any number of mutations. I would be concerned about off flavors from using to much of the slurry and would consider doing a smaller starter with less slurry and then build it up a level.

 

[bboykin87]

So I took your advice and only used a small amount of what I harvested and I started with an 800 ml starter. As you can see from the first picture it is definitely still viable, and the second picture shows there is a small amount of slurry on the bottom. I think I will chill and decant and pour 1200 ml of starter wort on it and see if it will propagate enough so I can harvest off the top and leave all of the slurry behind.

View attachment 1468150353919.jpg

View attachment 1468150367995.jpg

 

[ericbw]

Definitely make a starter and step up. It should be fine. There won't be any mutations because (presumably) the yeast didn't reproduce. Mutations happen from one generation to the next. Viability is the main concern.
If you can grow it from bottle dregs, this will work, too.