How To Fix Sourdough Starter Mold: Is That Even Possible?

Published Categorized as Sourdough Starter

So you’ve just gotten ready to bake some delicious bread when you notice some fuzzy spots in your sourdough starter. These fuzzy spots are mold. And if you’re wondering how to fix sourdough starter mold, then stick around, so that we can find out if that is even possible!

How to fix sourdough starter mold: is that even possible?

Table of Contents

Can Sourdough Starters Go Bad?

Yes, sourdough starters can certainly go bad. However, they don’t go down easily!

An established sourdough starter may appear healthy, but slight mishaps can cause problems.

Some of the main causes of starters going bad include inadequate feeding, cross-contamination, or simply a very humid environment.

Signs of a Bad Sourdough Starter

Once your sourdough starter is deemed damaged beyond repair, there is no coming back; you must discard the entire jar of sourdough starter, and start again.

Heated Above 120 Degrees

This happens more often than you’d think. Some of us desperate bakers attempt to find ways to quickly activate a starter. And while placing a jar of established starter in the oven with the light on may speed up the process, you could forget about it altogether. You may preheat the oven for something else, consequently killing your starter.

Yeast dies at 140 degrees F, so always make sure you remember where you’re putting your sourdough starters!

Bright Colored Streaks

Bright-colored streaks in your starter are a sign of severe neglect. When mold forms on a sourdough starter, it’s an indication that the bacteria in the starter has lost the ability to fight off the mold.

Once you notice a couple of orange or pinkish streaks it’s best to throw the whole thing away.

Inactive After Many Feedings

If you’ve fed your starter twice a day or every day for a week hoping to revive it, with no luck, then chances are it has gone bad. The best thing to do is discard and create a new starter.

How to Prevent Your Starter From Going Bad?

Here are some ways to prevent your sourdough starter from spoiling:

  • Don’t store your starter in an aluminum or copper container – always opt for clear glass containers, mason jars, or plastic containers. Finding the perfect jar might be a bit of a challenge, but once you’ve got it you’re golden!
  • Regular feedings feed your sourdough starter regularly, especially if you’re hoping for a healthy starter.
  • Store your starter in the refrigerator when you’re not using it – if you’re not going to use your sourdough starter for more than 2 days, then it’s better to store it in the refrigerator.
  • Don’t use an airtight container – a container with a tight-fitted lid can ferment the starter, preventing it from collecting natural yeast from the environment. Always cover with a loose-fitting lid or loose cloth.
  • Keep at room temperature when using – when actively using a sourdough starter, ensure that it is kept at room temperature, but try not to let it go above 75 degrees.
  • Use fresh, unbleached flour – flour may contain contaminants that can cause mold in your starter. To avoid this, use fresh, unbleached flour.
  • Weigh your ingredients – if you’re trying to revive an old starter, it’s better to weigh your ingredients in grams so that you have accurate proportions.
  • Use clean utensils and containers – this prevents contaminants that cause the growth of harmful bacteria.
  • Use filtered water – filtered water will prevent contaminants from spoiling your starter.
How to fix sourdough starter mold: is that even possible?

Troubleshooting Sourdough Starter Tips

If you find that you have done everything by the book when it comes to feeding your sourdough starter, but still no rise. Then some of these tips may help.

  • To revive an old sourdough starter, try feeding it with half bread flour or all-purpose flour, and half whole wheat flour or rye flour. Rye flour is especially great at making sourdough starter bubbly.
  • Your starter could be cold. Use a thermometer to monitor the temperature of the area where the starter is stored. If the temperature is below 65 degrees F, then find a warmer location. Another option would be to place a heating pad nearby for some additional warmth. But you must not exceed 75F.
  • A thin or runny sourdough starter may bubble but it will not rise well. It may rise and fall very quickly. Aim for a consistency that is similar to a very thick pancake batter.

Is My Sourdough Starter Moldy or Is It Something Else?

If your sourdough starter is moldy, you must throw it away and start over. This is because the bad bacteria have taken over your starter, so much so, that the good bacteria are unable to ward them off.

Your Sourdough Starter is Moldy

Pink, yellow, or orange streaks in your starter indicate mold growth. They can be lighter or darker in color but will always suggest that the starter has gone bad and must be tossed out.

Additionally, if you notice your starter has developed a furry, moldy layer on the surface of your starter, then unfortunately none of it is salvageable and it must be thrown away immediately.

Your Sourdough Starter is Not Moldy

  • A white powdery foam forming atop your sourdough starter is called Kahm yeast and is completely harmless. It is a normal result of growing natural yeast from wheat. Simply scrape it off and feed the starter.
  • Black or brown liquid atop your starter is called hooch, this is also safe, and a natural process of alcohol formation. You can either stir it in or pour it off.
  • Your sourdough starter will impart a variety of smells throughout its lifetime. Some of them will be pleasant, and others not so much. A bad-smelling sourdough starter indicates that your starter is very hungry, and must be fed immediately. If there are no signs of mold whatsoever, then it’s totally safe to feed and bake with.

How to Prevent Moldy Sourdough Starter?

  • Keep food or soap residue out. If you’re using the same utensils to prepare food as you do to scoop your starter, then this may be the primary cause of mold growth. Avoid mixing utensils, and always use a clean spoon to scoop or feed your starter.
  • Avoid neglect. If your sourdough starter has been unfed and refrigerated, then it should not cause mold growth. However, if you’ve left a starter on the counter for a couple of weeks with no feedings, it will most likely cause mold in your sourdough starter.
  • Keep it away from mold sources. If you have rotten food near your starter this could encourage mold growth on your starter.
  • Stay away from heat. Extreme humidity can also cause mold growth.
  • Use fresh flour and filtered water. Contaminants in the flour or water can also cause mold, so make sure you use fresh, unbleached flour and filtered water.

Signs of an Unfed Sourdough Starter

When a sourdough starter hasn’t been fed for a while, it can develop a small dark pool of liquid called hooch. Hooch is a type of acidic alcohol-like substance and a byproduct of fermentation.

While hooch is completely harmless, it is a clear sign that your starter is hungry!

Sometimes you may notice some white spots on the surface of your starter or just below the layer of hooch. As well as this, you may notice your starter emits an overpowering acidic smell, kind of like vinegar or nail polish remover.

There’s no need to panic when this happens, simply feed your starter as normal, and try not to neglect it again.

On the other hand, if your starter smells like something rotten, you should discard it immediately.

How to fix sourdough starter mold: is that even possible?

How to Revive an Old Inactive Sourdough Starter?

When it comes to reviving an old or inactive sourdough starter, you need to treat it like you would a brand-new starter. Essentially, you need to be patient and refrain from feeding it too often at first.

The starter will need some time to slowly rebuild its population, to feed the neglected and starved microbes. It may require additional feedings to become fully active.

The biggest mistake you could make when reviving an old starter is to feed it repeatedly throughout the day, in an attempt to wake it up.

Doing this is not only counterproductive but can remove some of the microbe colonies, before they’ve even had a chance to feed and multiply, therefore resulting in a weak starter.

Here’s how to revive an old sourdough starter:

  • If your starter has been stored in the refrigerator, remove it, and let it warm to room temperature, for several hours or overnight.
  • When a starter develops some hooch, you can either stir the hooch back into the starter or pour it off completely. If you’d like to bake sourdough bread that tastes sourer, then mix the hooch back into the starter for a more pronounced tangy flavor.
  • Give your starter a clean home. Simply transfer some of the old starter into another container before feeding it.
  • Reserve half a cup of starter for the next step, and discard the rest.
  • In a fresh container, combine half a cup of sourdough starter, half a cup of lukewarm water, and a light cup of flour. If you prefer to feed your starter by weight, then use equal weights of starter, flour, and water.
  • Place the starter in a warm location (70-75 degrees F).
  • Wait at least 24 hours to feed it again.

Best Container For Sourdough Starter

While the maintenance and health of a sourdough starter are very important, it’s container plays an important role in all of this as well! In fact, the type, shape, and cleanliness of a container can determine how well your sourdough starter will thrive.

Here are some of the things you must ensure when it comes to choosing the perfect container:

  • Clean – to prevent mold, ensure that your container is thoroughly clean, with no soap residue.
  • Non-airtight, but with a lid – your container should have a lid, though it shouldn’t be airtight
  • Non-reactive – no aluminum, or copper containers. Ceramic or glass containers are the best kinds of containers for your starter.
  • Largemouth container – containers with a largemouth are easier for scooping things out.
  • Large enough – ensure that the container is large enough to hold your starter, bearing in mind that your starter will be expanding with every feed.
  • Two suitable containers – it’s important to be able to transfer your sourdough starter to a clean container, once the current container has been washed.

So, How to Fix Sourdough Starter Mold

It may take a few trials and errors before you’re able to successfully feed and maintain a sourdough starter, eventually baking delicious sourdough bread. But with enough practice, you’ll soon become perfect!

How to Fix Sourdough Starter Mold FAQs

Why Did My Sourdough Starter Get Moldy?

The most common cause of mold on the sourdough starter is cross-contamination, from food or soap residue.

How Do You Keep Mold Out Of Sourdough Starter?

If you find that your sourdough starter tends to get mold, then here are some ways to prevent this: Change your flour, feed your starter regularly, and ensure that your hands, utensils, and surface is clean before feeding.

What Does Moldy Sourdough Starter Look Like?

Mold is typically fuzzy, and can have an orange or pinkish tinge.

How Do You Get Mold Out of a Sourdough Starter From a Jar?

Unfortunately, if you find that there is mold in your jar of sourdough starter, you will need to toss the entire thing out. Thoroughly clean your jar, before starting fresh.

By Natasha Krajnc

Hi! My name is Natasha and I'm specialized in home sourdough bread baking and currently based in Slovakia - a very small country in Central Europe. My bread baking story began in 2011 when I decided to give up commercial yeast. I felt tired all the time (especially after eating bread and other foods made with yeast), I wasn’t motivated to do anything, had trouble concentrating throughout the day, my abdomen was bloated and I was like a trumpet on steroids – basically, I was quite a wreck. I was a big bread lover (and still am) and having to stop eating bread was quite hard at that time but I felt I was on a right way to give my body a chance to heal itself.

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