Save Some Wort for Stuck Fermentation?

Recently, my buddies and I experienced a stuck fermentation. We decided to use WL099 to help finish off the fermentation, and it definitely helped, but didn't finish the job. After a bit of deliberation, we think a good idea for the future, just in case a stuck ferm happens again, is to save about 1.5L of the wort and refrigerate it (with intense attention paid to sanitation) to make a yeast starter. This will give the yeast a headstart with the same sugars it will experience in the stuck fermentation.

Our main curiosity is, will the wort stay the same in the refrigerator for those few weeks of fermentation? I'm always horribly concerned about sanitation, and I don't know if the chance at infection or a weird change in the wort is worth the risk of ruining an almost-done beer.

 

Toss it in the freezer instead. I freeze any extra wort from my mash for starters.

 

I don't know much about keeping wort, but I would at least second the freezing, and maybe say search around and see how other people do it (if they might vacuum-seal / use mason jars, etc), because I can tell you that I had kept some extra wort around in the fridge in a growler and after 3 or maybe 4 days it had gone sour.


But I'm not sure of the whole mission here - I would think usually if you have a stuck fermentation, it's going to be in a pretty big beer. And it's not really going to be the same sugars it's going to experience in the stuck fermentation, as a lot has happened in the "stuck" beer vs. when it was wort - different sugar picture, likely a decent alcohol %, etc. I'd say if you're going to make a starter to try to kick a stuck ferm into gear, really what you want is yeast cell count uber alles, and you just want to grow as much yeast as possible, which would call for normal step-starter methods. (Though I suppose if it was a big beer, you could dilute the saved wort to get it more into the "normal" range of a typical starter and save on DME/etc).

 

I third the freezing suggestion.

Think of it this way, is there anything you would keep in the fridge for three weeks that doesn't have preservatives in it or isn't highly acidic/basic?

 

I've read that some people will use a pressure cooker an store "canned wort" for easy use on starter day. That may be an option to help you out with your idea here too.

 

A second on the pressure canning. This is one of things on the list of proposed uses that convinced me to get a pressure canner.

If you don't have a pressure canner, the other option you have is to concentrate it to the point that stuff can't grow in it, but then you'd just be making your own LME.