How long will yeast last?

[C3Candy]

I opened a packet of yeast 2 days ago...has it gone bad yet?

 

[david_42]

Dry or liquid? If dry, it is probably ok.

 

[C3Candy]

It's dry yeast

 

[UTDoug]

I've used a packet of Montrachet for three batches of wine over the course of a year, no problems.

With liquid, I'd say a couple months. Yes, months. I've used half a vial or less on batches I knew would start well, and haven't had any problems. Sure, I've only done 11 batches of beer to date (not counting lots of wine) but I've done them all on 4 vials of WL. Optimally, you can cook about a gallon of starter and pour it into 4 bottles, put three in the freezer for future use, and then use a third or so of the vial to make a one quart starter.

 

[greg75]

I've used a packet of Montrachet for three batches of wine over the course of a year, no problems.

With liquid, I'd say a couple months. Yes, months. I've used half a vial or less on batches I knew would start well, and haven't had any problems. Sure, I've only done 11 batches of beer to date (not counting lots of wine) but I've done them all on 4 vials of WL. Optimally, you can cook about a gallon of starter and pour it into 4 bottles, put three in the freezer for future use, and then use a third or so of the vial to make a one quart starter.

My understanding is that freezing yeast kills it. The yeast crystalizes, damaging the cell membranes, or something of the sort. I'd recommend putting it in the fridge.

 

[Beerrific]

You can freeze yeast. You just to add a protectant to prevent damage due to ice formation. DMSO will do this but it isn't too easy to get or handle. Glycerol would be a good choice as it is safe to ingest.