Sourdough starter troubleshooting: What does it take to kill your starter?

“Did I kill my starter?” This is a surprisingly common sourdough question on our Baker’s Hotline. Novice and experienced bakers alike worry about the viability of their starters and call us for sourdough starter troubleshooting advice.

For many sourdough bakers, the underlying biochemistry at work in their starter remains a bit of a mystery. Thankfully, it’s quite possible to bake great sourdough bread while still being a little fuzzy when it comes to what’s actually happening in that little jar of starter.

The 6 to 10 days it takes to create a healthy and mature sourdough starter from scratch requires slightly more attention to “death threats,” because a fledgling starter hasn’t yet developed the defenses that characterize a mature starter. But once your starter is fully developed, it’s really pretty darn hard to kill.

And if you’ve purchased a sourdough starter from us, rest assured that it’s a mature specimen that will stand up well against unwanted bacteria or mold.

Sourdough Starter Troubleshooting via @kingarthurflour

Things that WON’T kill your sourdough starter

METAL: Stirring your starter with a metal spoon or placing it in a metal bowl won’t kill your starter. While we don’t recommend making or keeping your starter in contact with reactive metals like copper or aluminum, stainless steel is harmless. Sourdough Starter Troubleshooting via @kingarthurflourMILD NEGLECT: Missing a feeding or not timing the feedings exactly 12 hours apart won’t even come close to killing your starter. Please don’t ever set your alarm to get up in the middle of the night to feed your starter!

INCORRECT FEEDINGS: Feeding your starter the wrong amount of flour or water won’t kill it. While your starter may seem too dry or too wet, and may not rise the way you expect, no permanent damage has been done. You can correct its consistency by adding a little more flour or water, and then being more careful the next time you feed it.

BRIEFLY FREEZING YOUR STARTER: While there’s some dispute among sourdough enthusiasts about the benefits and/or dangers of freezing sourdough starter, a brief period in the freezer isn’t likely to kill a fully developed starter.

I recently froze a portion of my well-maintained starter a few hours after it was fed. Three days later I thawed it out at room temperature and let it continue to ferment. It was definitely sluggish at first, but after a second feeding it rose well and had a good aroma.

That being said, too much time in the freezer will definitely damage some of the wild yeast in your starter, and is also likely to kill off some of the friendly bacteria that contribute flavor. If you need to put your starter on hold for an extended time, we recommend drying your starter.

What does it take to kill a sourdough starter? When is it time to give up and start over? Click To Tweet

Things that WILL kill your sourdough starter

HEAT: If you allow your sourdough starter to ferment in the oven with the light on to keep it warm, and then forget it’s in there and turn on the oven, it’s unlikely your starter will make it out alive. Yeast dies at 140°F, and it’s likely that your sourdough starter will suffer at temperatures even lower than that. It’s best to maintain your starter at comfortable room temperature (around 70°F), though a little higher or lower won’t hurt anything.

SEVERE NEGLECT: If you neglect your starter long enough, it will develop mold or signs of being overtaken by bad bacteria. Mold can appear in various colors and is typically fuzzy in appearance. Bad bacteria is generally indicated by an orange or pink tinge or streak. Once your starter has lost its natural ability to ward off intruders, it’s time to start over.

Sourdough Starter Troubleshooting via @kingarthurflour

How to tell if your starter has gone bad

“Hooch” is the liquid that collects on the top of your starter when it hasn’t been fed in awhile. This liquid is the alcohol given off as wild yeast ferments. The presence of hooch isn’t a sign that your starter is in danger. However, it does indicate that your starter is hungry and needs to be fed.

When your starter is neglected for an extended period, the hooch tends to turn from clear to dark-colored. We get lots of calls from sourdough bakers worried about the safety or danger of various hooch hues. Is gray bad? What about brown or black? Surprisingly, none of these colors indicate that your starter has spoiled.

Sourdough-Starter-Troubleshooting via @kingarthurflour

See the orange streak? This starter shouldn’t be saved.

However, if you see a pink or orange tint or streak, this is a sure sign that your sourdough starter has gone bad and should be discarded. The stiff starter above was left out at room temperature for two weeks. It’s definitely time to throw it out and start over.

Sourdough starter troubleshooting: points to remember

1. Well-maintained mature sourdough starters are extremely hardy and resistant to invaders. It’s pretty darn hard to kill them.
2. Throw out your starter and start over if it shows visible signs of mold, or an orange or pink tint/streak.

I hope you’ll share your own sourdough starter questions and discoveries below. There’s always more to learn when it comes to sourdough!

And please check out part 2 of this sourdough starter troubleshooting post!

Barbara Alpern
About

Long time professional artisan bread baker, caramel maker and member of our Baker Specialist team, Barb grew up in Ann Arbor, Michigan and has four grown sons. She has baked in Michigan, Maine, Vermont, and Texas (if you count baking cookies for her son's wedding!).

comments

  1. Angelo L Bauza

    My sourdough is 2x the size that it normally is and it has happened again this weekend. I am not sure what is going on

    Reply
    1. Barbara Alpern, post author

      Hi Angelo, it’s normal for your starter to slowly rise and double in size after having been fed with fresh flour and water. If this is what you’re observing, then all is well. For more help troubleshooting your starter’s behavior, please give our Baker’s Hotline a call at 855-371-2253. We’d be happy to talk sourdough with you!
      Barb

  2. Daron

    I have a healthy 3 year old starter that I transferred to clean it’s home (a crock) and in the 12 hours it rested waiting to be fed I found 1 single pink dot. I scraped it out and fed it and it seems normal…. I’m hesitant to toss it since it’s been my trusty bread making companion for so long. How will I know if it’s not safe?

    Reply
    1. Barbara Alpern, post author

      Hi Daron, if you only saw a tiny pink spot, and you haven’t seen any more signs of trouble, your starter is probably fine, but you might want to do a day or two of twice a day feedings at room temperature to be sure it’s solidly healthy. If the spot was some sort of unfriendly bacteria, it might be a sign that your starter is a little vulnerable, and a few days of twice a day feedings at room temperature will help restore it to good health.
      Barb

  3. Lynn Bradley

    How long does it typically take for my sourdough starter to be ready to bake with? I started on Thursday, today is Saturday, I have been feeding it twice a day. Also, when I’m ready to store in the refrigerator should I feed it first or just store it?

    Reply
    1. Barbara Alpern, post author

      Hi Lynn, is this a starter you’re creating from scratch, or one that you ordered from us? If you’re just reviving the starter we shipped to you, then it’s quite likely your starter is ready to use in your baking. Look to see that your starter is doubling in size 6-8 hours after you feed it at room temperature. When you’re ready to store your starter in the refrigerator, give it one more feeding and then let it sit out at room temperature for 2-4 hours, or until it begins to bubble, before placing in the refrigerator.
      Barb

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