The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

moldy starter!

jenniferw's picture

moldy starter!

Im so irritated, Ive had a good starter going for several months now and I just opened my container and realized its covered in mold all around the lid and inside! There wasnt any mold on the starter itself though.... Is it ruined or can I still salvage it???

Matt H's picture
Matt H

I'd chuck it and start over. You don't want to mess around with mold spores.

polo's picture

From what I've read and experienced there is no need to abandon your starter. When I first started mine I saw some mold on the side of the jar and near the top  (about day 4  or 5). I transferred a bit of my starter to a clean (sterilized) jar and moved on from there. I have not seen any traces of mold since, and my starter is just fine. I realize that your starter is older, but it is worth giving it a shot.


Daisy_A's picture

Hi jenniferw,

That must have been frustrating!

There are two main trains of thought on this one - the first being that most starters can be rescued and the second that some moulds can be toxic and can spread more widely than is apparent at first glance, so best to start over.

On the first one. This thread from Brian Dixon suggests that most viable starters can be 'cleaned' by starting again with a very small amount and also sometimes swilling it quickly in hot water.

I would have gone with this method until I was following up a problem of mould on a bucket of malt extract and read info. on moulds on some brewing sites.

These said that as moulds send out spores and excrete toxins, parts of the product that don't yet appear mouldy can still be infected already with mould spores. Moreover they also said that not all moulds are killed by heat. Some can become more toxic when heated. So that information favours the 'don't mess with mould' approach.

One solution with malt, apparently, apart from refrigerating it (which wasn't recommended on my pack), is to float some vodka on the surface of unused malt to form a barrier against mould. Or so some brewers suggest.

Obviously won't work with yeasts. One bit of advice I was glad to read early on in sourdough culturing, however, was to sterilise the lids just as well as the jars and to choose lids that were easy to sterilise. Sounds like your problems might have started around the lid?

Whatever you choose to do, hope you soon have a healthy starter again.

Kind regards, Daisy_A


manicbovine's picture

This just happened to me because I skipped a feeding. I'm generally forgetful, so it's not the first time.


Mine smells cheesy when this happens. I've rescued it several times by saving a 2 teaspoons and feeding as normal, but every 8-12 hours. It normally springs back to health after 4 feeding cycles. 

I've never had mold all over the container, so who knows. 





Mike Avery's picture
Mike Avery

This is what I've done with good results.  Wash a handful of spoons.  Ones long enough to reach to, and a bit below, the starter.

Mold is generally a surface condition - if you read medical history a major issue in cultivating anti-biotics was that mold usually stays on the surface so the yields were too low.  For us, this is good news as the starter is likely to be intact.

Scrape off the mold from the surface of the starter.  Change spoons frequently.

If the top of the remaining starter is discolored , scrape that off with fresh spoons.  You want to get to a light colored layer.

Once you are into the light colored layer, use a fresh spoon to take out a teaspoon of the remaining starter and put it into a clean bowl.  Put the rest of the starter back into the fridge in case you need to repeat this process.

Whisk in 1/4 cup of water and then 3/8 cup of unbleached white all-purpose flour.  I don't suggest whole wheat starter because that adds too much of a biological load to the starter and makes it likely you are starting a new starter rather than reviving an old one.  If you weigh ingredients, I use equal amounts of flour and water.  About 50 grams of each would be good.  (If you think that's not the same as the cup measurements, you're right.  Scoop the flour aggressively to compact it as you measure it - you should have about 60 grams each of flour and water.)  The starter should be fairly thick, like heavy cream maybe.

Cover it, 8 to 12 hours later add another 1/4 cup of water and 3/8 cup of flour.  After that, every 8 to 12 hours discard half and then feed another 1/4 cup of water and 3/8 cup of flour.

It should revive in a few days.  You're looking for a starter that will, at least, double in size between feedings (which is one reason I suggest a fairly thick starter).  If not, try with a freesh spoon of starter from the jar that you saved in the fridge.

Prevention is the best thing here.  Refrigerated starters last better if -

  • you feed the starter just before you put in into the fridge

  • you make the starter quite thick - like 60% to 50% hydration and

  • you take it out and refresh if from time to time - no less than every 2 months or so.

Hope that helps!



jenniferw's picture

Thanks for the info everyone!