Oh no! I froze my vile of liquid yeast.

[waverz]

Hit the lhbs before work the other day and and forgot the vile of wyeast in my truck. It was well below zero that day abd needless to say the yeast froze after 8 hours.

I put it in the refrigerator to thaw but how can I tell if it's still alive?

Any advice would be great. Was really wanting to brew with it this weekend. Maybe it would be best just to go buy another vile?

 

[adamdillabo]

Or make a starter. Asap

 

[CRoth36]

A new vial isn't a bad idea. I've never froze yeast before so I can't speak from experience. Try getting on the manufacturers website. They usually have tons of info on stuff like that. If you do decide to use it I would definitely make a starter. If it's a smack pack just let it untoward and smack it. If it swells it's probably good.

 

[waverz]

Guess I need to Google how to make a starter. It's not a smack pack. I might be better off just picking up another vile in the morning before I brew.

 

[Malted_hops]

I would go get another vial. While the knowledge of how to make a starter is good to know, I wouldn't want to be under the pressure to make one correctly, under a deadline, with possibly (more than likely) a damaged pack of yeast.

 

[LabRatBrewer]

+1 on the starter, always a good idea with liquid yeast even if the yeast weren't left out in the polar vortex. Here's a how to: https://www.homebrewtalk.com/f39/how-make-yeast-starter-pictorial-76101/index10.html

 

[masskrug]

How cold did they get? Let them warm up in the fridge for a day, then bring them outside into a starter. I bet some of them come to life.

 

[whitehause]

Just throwin it out there, but when you un-freeze yeast from a frozen yeast bank, it's best to warm it up quickly. Now that yeast is stored in a glycerin solution, so I'm not sure how just plain frozen yeast will deal with that. If it's a yeast you use often, grab another one, but pitch the one you have also. Without a starter, you should probably use two anyway. While that batch is fermenting, look up the sticky on yeast washing and on making starters. Get those two things down, and you'll never have to run to the LHBS for that yeast again.

BTW....by warming quickly, I just mean in a glass of room temp water, not the microwave or anything crazy

 

[kh54s10]

When yeast is not prepared with glycerin for freezing the cell walls get damaged killing them. You might have some viable yeast and it is possible you could propagate by making a starter. But, since you have stated you know nothing about starters I would not suggest you learn with this vial.

I suggest you get a new vial or two and go with that. You really should make a starter.

For the frozen vial you could try a small ~250 ml starter and see if it ferments then you could step up to a proper size.

Check out mrmalty.com and yeastcalc.com for information on making starters.

 

[ram5ey]

You lose 10% viability with each freeze thaw cycle. Assuming it's not an old vial (check mr. Malty) you will be fine. Make a starter. (Info on yeast freeze viability from interview with Chris White on Brewing Network)

 

[BostonianBrewer]

When yeast is not prepared with glycerin for freezing the cell walls get damaged killing them. You might have some viable yeast and it is possible you could propagate by making a starter. But, since you have stated you know nothing about starters I would not suggest you learn with this vial. I suggest you get a new vial or two and go with that. You really should make a starter. For the frozen vial you could try a small ~250 ml starter and see if it ferments then you could step up to a proper size. Check out mrmalty.com and yeastcalc.com for information on making starters.

. What he said

 

[PRE66_6TART]

You lose 10% viability with each freeze thaw cycle. Assuming it's not an old vial (check mr. Malty) you will be fine. Make a starter. (Info on yeast freeze viability from interview with Chris White on Brewing Network)

I can't figure out how to copy the quote on this app, but I've seen a statement from white labs saying the same thing. You only lost 10%. That being said using only one vial in a 5 gallon batch is already pushing it, even if it's 100% viable, so a starter is probably a good idea. Or if you're going to just buy more yeast, I would pitch them both, which would probably get you closer to right pitch rate, assuming this is a five gallon batch. If you wanted to brew this weekend you might have to do it this way, since you're running out of time to get a starter started.

 

[Vigo_Carpathian]

Freezing/thawing yeast results in MUCH more than 10%loss in viability. That number is waaaaay off. If that was the case there would be no point in using glycerol. Even with glycerol you can expect around 50% to die. The glycerol stocks I work with typically have only a 10% survival rate after freezing at -80C. The survival rate will be better at -20C though (standard freezer temps). That being said, there still will be some alive to revive. You should make a small (250ml) starter and then step it up to a 2L starter before pitching. 1/4 cup DME per 400mL water.

This link has charts of survival rates from freeze/thawing brewer's yeast with glycerol.

http://nbimcc.org/JCC/2002/JCC312.pdf

 

[ram5ey]

I got the 10% thing from an interview with Chris White of White Labs so I'm assuming he wasn't making it up (plus he has no reason to, since if the yeast was bad he should suggest buying more of his product). I'm also sure there is a difference between freezing for storage and a freeze thaw cycle over a few hours. PRE66 is right though that one vial usually isn't enough anyways and depending on the gravity you might need one or two other vials if you are not making a starter.

 

[whitehause]

I got the 10% thing from an interview with Chris White of White Labs so I'm assuming he wasn't making it up (plus he has no reason to, since if the yeast was bad he should suggest buying more of his product). I'm also sure there is a difference between freezing for storage and a freeze thaw cycle over a few hours. PRE66 is right though that one vial usually isn't enough anyways and depending on the gravity you might need one or two other vials if you are not making a starter.

I have to assume that he was talking about yeast that was prepared for freezing in his yeast bank with a glycerin solution. The OP left a vile in his car, and the vials don't have glycerin in them.

 

[ram5ey]

No. He was advising a caller that asked this same question.

 

[jonmohno]

I would make a step starter and see what happens. Unless money and a little time are not an issue for you and you dont want to deal with it. Or if you just dont want to deal with it use a backup yeast or buy more.