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. John

    Hi Barbara, just about every starter that I have made has turned orangey pink. I know that this is not a good thing and so I discard the starter and then try again – and it happens again. What is actually causing this to happen? I am using stoneground rye but assume that any flour can be used and would not cause this to happen, I am storing it in a glass jar with a metal lid and mix up any new starter with my cleaned hands and then add it to the jar using a metal spoon. Any help as to what is the chemical process in the mix that causes this discolouration and any thoughts as to where I am going wrong would be very much appreciated. Thanks. John

    Reply
    1. Barbara Alpern, post author

      Hi John, you didn’t mention how often you’re feeding your starter, or at what temperature, but the pink/orange hue could be a sign of unfriendly bacterial growth, which could be related to infrequent feedings in warmer temperatures. Since wholegrain flours tend to ferment more quickly, they do require a little more vigilance in terms of the sourdough feeding schedule. If your starter is still early in the creation process and isn’t rising much, you should be able to get by with one feeding a day, but if your starter is rising and falling predictably, then you’ll likely need to feed it twice a day. Try to feed the starter when it’s at its peak of rising, or just as its beginning to fall. If your starter is developing liquid on top (hooch) between feedings, this is a sign that too much time is elapsing between feedings. If you happen to live in a very warm climate, you may need to take extra precautions to keep your starter a bit cooler. It should be fine in temperatures between 68-80 degrees, but if it’s rising more quickly than you can keep up with, you may need to feed it with cooler water or refrigerate the starter when you’re not able to feed it in a timely fashion. If all else fails, you may have better luck purchasing a mature starter from us. A mature starter will be more resistant to unfriendly invaders than a fledgling starter and you may find you have less trouble maintaining it. For ease of care I would recommend continuing to feed it with our unbleached all-purpose flour, but if you’re after a rye starter, you could certainly convert a portion of the starter by feeding it with rye flour. If this doesn’t sound like what’s going on with your starter, please give our Baker’s Hotline a call at 855-371-2253. We’d love to help you troubleshoot!
      Barb

  2. Jayne

    Thanks to this thread, I revived a long-dormant starter. I appreciate everyone sharing their experiences. I got the starter out, put it in another container, washed the crock thoroughly and then put a little bit of the starter back and fed it and left it on the counter overnight. By morning, it was bubbly and active. I won’t have my kitchen back together for baking for another several weeks, but I’ll keep it fed and happy until I can be baking again.

    Reply
  3. Mick

    My starter was doing great except on day 6 it started to get less active. It was pretty cold in the house so I wrapped some old school Christmas lights around it yesterday around 4pm. I woke up this morning and the jar was so hot! It had formed a yellow crust on the top that I scraped and threw away. I stirred it up and have the lid open now. Did I kill it?

    Reply
    1. Barbara Alpern, post author

      Hi Mick, heat is the one thing that is certain to kill a starter, so if your starter got hotter than 140 degrees, it may be dead. However, if it starts bubbling nicely after this episode of heat, it may be fine. I would give the starter another feeding, cover it well so it doesn’t dry out on top, and wait to see if you see any bubbling over the next 12 hours. If the starter remains flat, it’s probably dead. In future, if you can find a spot for your starter that’s between 68-80 degrees, that would be ideal. The oven with the light on may work, or you can place some boiling water in your microwave to heat up that smaller space, and then allow your starter to ferment in there. Just don’t turn on the oven or microwave while your starter is in there!
      Barb

  4. Ruby CB

    Hi there,
    This is my first time making a sourdough starter and it’s super liquidy, it doesn’t rise, and there aren’t many bubbles. I’m assuming it’s not working, but I don’t know where I went wrong!
    Thanks!

    Reply
    1. Barbara Alpern, post author

      Hi Ruby, you didn’t mention at what point you are in the starter-making process, so it’s hard to say exactly what’s going on. The starter does tend to get more liquidy as it ferments and becomes more acidic, so this may not be a bad sign. Often around day 4-6 you’ll see less activity and little rise, although the starter will still bubble. The thinning out that you describe may be a sign that the acidity is increasing and the wild yeast is about to kick in. If that’s where you are, then I would recommend continuing with your twice a day feedings until the starter begins to rise predictably and doubles in size about 6-8 hours after having been fed. Once your starter is rising in this way, you can begin to bake with it, although continuing to feed it for a few more days may help develop more flavor potential. If this doesn’t sound like what’s going on with your starter, please give our Baker’s Hotline a call at 855-371-2253, so that we can help you troubleshoot more directly.
      Barb

  5. Janice

    My starter is about 4 weeks old. I live in Florida and the days are getting hotter (85F) outside where I have maintained it. The reason that I keep it outside is that the temp in our house in the evening is 67F. I pulled off a cup to bake bread about 10 days ago and after that it has not been doubling in size and the very tangy scent has turned sweeter. Do you have any suggestions? Thank you for your help.

    Reply
    1. Barbara Alpern, post author

      Hi Janice, I don’t think 67 degrees at night should be an issue with your starter as long as it’s in the 70’s during the day. You can feed it with slightly warmer water in the evening, or stick it in a more protected spot when your house is on the cool side (like the microwave, or in the oven with the light on). I think that would be a safer environment than outdoors when the heat is climbing over 85 degrees, as long as you’re careful not to turn on the oven or the microwave while the starter is in there! Try keeping your starter in the 68-80 degree range and see if this improves its rise. The aroma varies quite a bit, depending on what point it is in the fermentation process after having been fed, but I wouldn’t worry too much if it doesn’t smell terribly sour.
      Barb

  6. Ellen Fitzgerald

    My son and I started a sourdough starter on sunday. It is now Tuesday (day 3) and I’ve seen pink dots in the starter after two rises. It has a very strong smell (not necessarily pleasant) and has been very active with bubbles already. Any suggestions?
    It’s been quite warm in our area, but our weather has cooled back into the 70s/80s for the next week or so. Can room temperature be too warm for starter?
    Thanks!

    Reply
    1. Barbara Alpern, post author

      Hi Ellen, if you’re seeing pink spots so early in the process, I would start over. Be sure to clean your utensils and container with very hot water before trying again. It’s possible that the hot weather may have had something to do with your starter going wrong, so if you can keep your new starter somewhere that stays in the 70’s during the creation process, that may work better for you. It can definitely be challenging to create and maintain a starter if your environmental temperatures are always in the high 80’s or 90’s. The issue is that you don’t want your starter sitting out in very warm conditions without being fed regularly and it can be hard to keep up with a starter that ferments very rapidly. Using cooler water to feed the starter may be helpful, and if it rises too quickly, sticking the starter in the refrigerator until you’re able to feed it again may be necessary. The ideal when maintaining your starter at room temperature is to feed it when it’s at its height of rising, or just as its beginning to fall. In very warm climates it may be necessary to reduce the percentage of starter as compared to flour and water you feed it, in order to slow down fermentation.
      Barb

  7. Lily Benson

    How long does it take for a starter to make really sour bread as my bread is never very sour, my starter is just over a week old, I don’t feed it too regularly, only when I bake with it which has been twice. Do I need to feed it more or just wait for it to mature? It smells very alcoholic.

    Reply
    1. Barbara Alpern, post author

      Hi Lily, it takes at least 10 days for a starter to fully mature, which will allow for a more complete flavor profile, so your starter might well benefit from a few more days of twice a day feedings at room temperature. In addition, feeding your starter more often at room temperature will build healthy populations of both yeast and friendly bacteria, that can contribute more to the flavor and rise when it comes to baking your bread. We like to emphasize maintaining a healthy and active starter, and then trying to manipulate the flavor later in the process (in the preferment and dough phases). Things you can do during the dough phase that may increase the sour flavor: substitute a small percentage (10%) of whole rye or whole wheat flour for part of the white flour in the recipe, proof the dough at slightly warmer temperatures (78-80 degrees), try doing the shaped rise in the refrigerator overnight and baking the next day. We’re working on a blog post about sourdough flavor development, so stay tuned! In the meantime, you might want to try our Extra-Tangy Sourdough Bread recipe or our No-Knead Sourdough Bread recipe, as these two recipes tend to deliver more sour flavor.
      Barb

  8. Kimberly

    Please help: my starter seemed to be doing great for the first few days. It was rising, bubbling and smelled good and yeasty. I was feeding it accurately weighed amounts of flour and warm water using a digital scale. Then, after a feeding in day 5 it failed to raise. It’s now day 10, I’ve been refreshing it every 24 hours. The starter is not reacting much. It’s starting a firm lump. There are a few bubbles that I can see through the bottom of the glass bowl and the top has a light grey film that I scraped off before measuring out my starter to use in the refresh. But it’s not raising. Should I scrap it?

    Reply
    1. Barbara Alpern, post author

      Hi Kimberly, it sounds like your starter hit a lull, and the wild yeast may not have fully kicked in yet. Often early activity like you observed in your starter can be due to bacteria that give off carbon dioxide, rather than the wild yeast. To encourage the wild yeast, it may be helpful to alter your feeding regimen to cultivate more acidity. Don’t worry too much about the grey film you’re seeing, which is probably just due to oxidation. If you’re not already covering the bowl well with plastic wrap, I would recommend doing so. For the new feeding routine: try going back to feeding your starter with just whole wheat flour once a day, but switch the ratio of ingredients to 2:1:1. So, you’ll be saving 4 ounces of stater and feeding it 2 ounces of flour and 2 ounces of water. Continue feeding in this way until your starter rises in a predictable fashion after feeding. At that point you can switch to feeding with the 1:1:1 ratio of 4 ounces each of starter, flour and water and begin feeding twice a day with all-purpose flour. It may take a few more days for your starter to adjust to the all-purpose flour and begin to rise predictably, but once you see that, you should be good to go!
      Barb

  9. Laurel

    I left my sourdough starter in the fridge for 2 weeks while on vacation. Took it out had grey on top. Skimmed it off. Took under portion out and put in new container and fed it. Next day had grey again on top and mixed throughout it. Skimmed of top for next week and fed daily. Still has grey spots throughout, is it ok? Or should I throw out?

    Reply
    1. Barbara Alpern, post author

      Hi Laurel, grey is generally not a problematic color and is usually a sign of oxidation. I see this most often on top of my whole wheat starter when it’s been left in the refrigerator for several days. Is this a white flour starter, or does it contain some whole rye or whole wheat? Since leaving your starter in the refrigerator for two weeks won’t normally cause any issues, I suspect your starter is just fine, but it worries me a little that you’re still seeing grey spots throughout after feeding it at room temperature for a week. If you were only feeding once a day at room temperature, you might want to try a few days of twice a day feedings. Is the starter rising well, and does it have a pleasant aroma? If all else looks good, you’re probably fine to use it, but If you want to send a photo of your starter for me to look at, you can attach a photo to an email sent to customercare@kingarthurflour.com. Put “ATTN: Barb” in the title, and I’ll be sure to see it.
      Barb

  10. Susan

    Hi. Is it okay to feed my starter with white whole wheat flour or bread flour? I don’t always have plain all purpose on hand. How will the use of the other flours you offer affect the ripening? Thank you.

    Reply
    1. Barbara Alpern, post author

      Hi Susan, the more consistently you care for your starter, the healthier it will be, and a healthy starter will behave more predictably and reliably in your baking. Switching up the type of flour you feed your starter causes the microorganisms to have to adjust and this can slow the starter down. This isn’t the end of the world, and it will certainly not cause permanent damage to your starter, but it’s not ideal. A starter fed with whole wheat flour tends to ferment a bit more quickly (once it’s adjusted to the new feeding routine) and will have more of a sour aroma. Bread flour will likely give you a slightly stiffer consistency and won’t provide your starter with quite as good of a meal because the starch content is lower in bread flour as compared to all-purpose flour. All that being said, if it’s between feeding your starter or letting it go hungry and waiting for the correct flour, your starter will likely appreciate a feeding.
      Barb

Post a comment

Your email address will not be published. Required fields are marked *