Does Sourdough Starter Go Bad?

There are many different processes and biochemical reactions taking place in a starter as it matures. It is not fully understood, and it is a bit of a mystery as to what is really happening within the jar. Thankfully, even with this confusion, it is still possible to make great sourdough bread without clearly explaining how the process takes place.

A sourdough starter can go bad if severely neglected or left at a temperature above 110°F. If it forms mold and harmful bacteria indicated by color change, it needs to be discarded. If it is mildly neglected, incorrectly fed, briefly frozen, or forms a hooch, it can still be revived and saved. 

Note: If you did neglect your sourdough starter there is no reason to dispair, you can still save it! Just have a look at my article “How to Revive a Neglected Sourdough Starter?“

The maturity level of your starter will impact its resilience and ability to survive. There are certain conditions your starter can survive and others where it cannot. It is essential to know when a starter can be saved and when it should be thrown away if it is unsafe to consume.

What Can Cause A Starter To Go Bad?

It can take roughly 6 to 10 days for a starter to reach its initial maturity level, where it can be used in baking. Your starter will need the most attention and care during this stage of life because it is easy for it to die if neglected during this period. It can die because its microbes are still growing and maturing, and the starter is still developing its defense mechanisms. 

Once your starter has passed this initial stage of maturity, its survival rate is much higher. It is helpful to know what can and can’t kill it to make sure your starter reaches its full maturity and can survive for a long time. 

What Can’t Kill Your Starter?

Below is a list of things that will not kill your starter:

• Metal: your starter won’t die if you stir it with a metal spoon or keep it in a metal bowl. It is not advised to let your starter be in contact with any reactive metals for long periods when making it or while it is stored. These reactive metals include copper and aluminum; stainless steel is harmless to a starter.
• Minor neglect: feeding times for your starter that are not precisely every 12-24 hours won’t kill your starter. Don’t worry or stress if you forget to feed it at the correct time every day.
• Feeding inaccurately: your starter won’t die if you feed it the incorrect amounts of flour or water. Signs that indicate if it has been under or overfed are that it looks too dry or wet, and it may not rise properly. 

Feeding your starter incorrectly will not kill it unless it is underfed for an extended period. If it is underfed, then feed it again with the correct amount of food, and if it is overfed, let it sit for a longer period before feeding it again. It is vital to make sure it is fed correctly for the next feeds. 

• Freezing a starter: a brief period of freezing a starter won’t damage your fully matured starter. When you take it out of the freezer, leave it to thaw fully and feed it to improve its strength. 

If you leave your starter in the freezer for too long, for over a year, the wild yeast and good bacteria will eventually die. If it needs to be stored without feeding for longer than a year, it would be best to dry it out. 

Note: If you want to read more about what you need to look out for before freezing your sourdough starter, check out my article “Does Freezing Harm Sourdough Starter?“

What Can Kill Your Starter?

Here is a list of elements that can kill a starter:

• Heat: your starter can die if it experiences temperatures over 110°F, this is because these high temperatures kill the live yeast and good bacteria. A typical instance where it may experience this is when it is left in an oven that is off for it to warm up and left in there by accident after switching the oven on. An optimal temperature to keep your starter at is 70°F.  
• Severe neglect: if you neglect your starter for too long, it can die because it can result in mold and harmful bacteria growth. The signs that indicate the growth of mold and bacteria are if its color changes or it has a fuzzy appearance. 

If this happens, it won’t be able to protect itself anymore, and it will need to be thrown away as it is also unsafe for consumption. It is best in this instance to start from scratch and make a new starter.

How To Tell If Your Sourdough Starter Has Gone Bad?

There are specific characteristics that you can look for to identify whether your starter has gone bad. It helps be aware of specific instances where your starter can be revived and others where it should just be thrown away. 

Your starter has not gone bad if it doesn’t or if it stops forming bubbles for a few days. This is expected in the first few days of its life; continue feeding as per usual, and they will come back. 

A sign that indicates you have not fed your starter for a long time is a layer of liquid forms on the surface called a hooch. A hooch is liquid alcohol that forms when the wild yeast starts to ferment due to oxygen deprivation. 

It may look a bit gross to have a layer of liquid sitting on your starter, but there is nothing to be worried about; this doesn’t mean your starter will die. If the hooch is left too long on the surface, it will change into a dark color; this color doesn’t indicate it is dying. Mix the hooch into your starter and feed it; remember to feed it more regularly to prevent the hooch from forming.  

As was discussed above, mold and harmful bacteria will form if your starter has been severely neglected for an extended period. You will know that there is mold or harmful bacteria in your starter if the color has changed or if there are spots of different colors in it. 

If mold starts to grow in your starter, it will have specific colors and a fuzzy appearance. When bacteria grows, it can be seen with a tinge or streak of an orange or pink color. Once this happens, your starter will become weak and unable to protect its self from any intruders. The growth of mold and bacteria is not acceptable to eat and so it is best to throw it out and start again.

How To Revive Your Starter?

It can be beneficial to know how to look after your starter correctly so that it does not go rancid and learn how to and when to revive a starter that has gone bad.

How To Care For Your Starter?

Knowing how to look after your starter properly will lower its chance of going bad and dying. Here are some ways to look after it:

• You must feed your starter every 12 to 24 hours. If the weather is too cold, it should be fed once a day. If the weather is hot, it should be fed twice a day. 
• The sourdough starter should be kept at a temperature of 70°F. If it increases to a temperature of 85°F or over, the yeast will start to die. 
• Feed the starter correctly; if you feed it the incorrect amount of ingredients every time, it can result in a bad starter.

Note: Did you ever worry to overfeed a starter? If the answer is yes, you can check out my article “Can You Overfeed A Sourdough Starter”

How To Bring Your Starter Back To Life?

If your starter has gone rancid, it can be revived unless its color has changed, indicating mold and bacteria growth. This should be discarded. It will take extra time, attention, and care to nurse your starter back to life. To help bring your sourdough starter back to life, try the following methods:

• Scrape off the discolored skin that has formed on the top of your starter and discard it. If it is not removed, then it can cause your starter to change color. 
• Stir the liquid hooch into the rest of your starter that formed on the surface. 

• Keep your starter at an ideal room temperature of 78 to 80°F. You can make sure it stays at this temperature by putting it in a proof box, keeping it insulated, or feeding it with warm water. 
• Before feeding your starter remember to discard some of it; this will lower the number of bacteria competing for the nutrients, increasing its chance of reactivation.   
• Feeding your starter a few times will activate the microorganisms; it is essential to time these feeds right. You may need to give your starter an extra feed every day to revitalize it; if you usually feed it once a day, instead feed it twice. Once it is looking active and healthy, then you can go back to its routine feeds.

The starter must not be fed more than three times per day. If this is done, it will cause the bacteria and mold to increase because the yeast and good bacteria we want will not have enough time to consume the nutrients. 

If you feed your starter too often, it can lead to a reduction in fully metabolized yeast and good bacteria. If you feed it too late, it can become very acidic and form an unfavorable environment for the yeast to grow.

• Feeding your starter with high-quality rye flour can help bring it back to life. You can replace half the flour given with rye flour.  
• An organic flour can also be used; this is free of pesticides and chemicals that can help activate your starter.

Be patient and give your sourdough starter time to reactivate; soon, it will be healthy and ready to use. 

Conclusion

Your starter is very resilient once it has fully matured. It is good to know how to care for it optimally to ensure it is healthy and safe to use.  

It takes time and attention to care for your starter correctly, but it is rewarding in the end. You can consider other ways to store your starter, reducing the attention it needs, especially if you have a busy schedule or are going away.  

Taking proper care of your starter will ensure that its flavor is satisfactory and that your baked products will rise and be a perfect consistency. The hooch is not always a bad thing to have sometimes, as it can help improve your starter’s tangy sour flavor.

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