The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Freezing Starter: How long will it stay good?

jey13's picture

Freezing Starter: How long will it stay good?

Yo, all. I had a situation where I had to re-create my starter, and luckily, had plenty hydrated. I did so, and once my starter was restored, I decided to augment my starter safety net by putting some away in the freezer.

Can you tell me how long it will last in the freezer so I can replace it when it’s time? 

idaveindy's picture

I actually tested mine, (Cultures for Health, Whole Wheat) freezing a small sample every 2 to 4 weeks, and marked the date, and tried to revive it.  5 months was the limit.  But....

Everyone's starter consists of different species and strains of wild yeasts, and different species and strains of bacteria.  And they all react differently to freezing and at different sub-freezing temperatures.  Some of those yeast and bacteria cells will survive for a while, some will burst/die due to water in the cells expanding as it freezes..

And since a starter can have multiple yeasts in it, and multiple bacteria in it, some will survive and some won't -- hence your revived starter will likely be a different mix, different quality, different attributes, than what you put in the freezer.

Ed Wood's book goes into better explanations.  He says: don't use freezing method.

So while "between 1 and 5 months" might be technically true, or "good enough" in some situations, it's just not going to reliably be the same, no matter how long/short of time  you freeze it.  It's a roll of the dice...  it "just might" work out ok, and it might not.

The best way is to dry it.  Supposedly it "sporifies", but there is debate about that too.   I used one of the methods from youtube, spreading a thin layer on parchment paper or wax paper (made it watery to get it thin) and let completely  dry for 36-48 hours in cool oven, then  crunching into small granules.

BobbyFourFingers's picture

+1 for drying it. Several times now I’ve stored my different rye starters by placing a food-safe desiccant bag in with the dried starter then vacuum sealing it, and labeled it for posterity. They should be good for over a decade.

I haven’t reconstituted them but I have no reason to think there will be any problems as this method is far more gentle than freezing.

Maverick's picture

Dehydrating  is the  way to go. It will last as long as you need it. Freezing is a mixed bag because you run the risk of killing the  starter. I am sure some have had success, but why chance it when dehydrating is so easy.

julie99nl's picture

I have some vacuum packed in the freezer and revived it once and it came back to life much faster than my dried starter. I vacuum seal almost everything in the freezer so that helps eliminate ice crystal damage, but in truth I've never tested how long it would survive.
My dried starter took a good 5 days to come to an acceptable level of activity (for me).
My freezer starter was probably a lot less mature. During the whole drying process, it's still in an ideal temperature range for fermentation so it's completely exhausted once reconstituted.

jey13's picture

I do have a jar of dehydrated starter. But I wanted to have a second back-up. I do take all your points about freezing not being the best idea—especially if you can’t vacuum seal, which would certainly protect the starter’s integrity as much as it can be protected when frozen. 

I’ll re-think the freezing and make another batch of dehydrated.