Is Homemade Sourdough Bread Safe?


When a friend of mine became pregnant, she worried that sourdough bread would not be safe for her or her baby to eat, as it naturally contains millions of bacteria in it. This intrigued me and I did a little research to find out if there was any weight to this anxiety she felt.

So is homemade sourdough bread safe to eat? Although sourdough bread does contain billions of bacteria, this type of bread has been eaten for thousands of years in homes all around the world. It’s been traditionally shared with children and elderly alike, without restriction. And ofcourse, for the majority of time, this would have been a sourdough bread that was made at home, with bacteria and yeast found in homemade sourdough starters. So in all liklihood, as long as the bread has been made correctly, it should be perfectly safe to eat.

But that doesn’t mean you can roam free and eat anything with bacteria in it. Sourdough bread, if made at home, has to have been made correctly for it to be safe to eat.

How Do I Know Homemade Sourdough Bread Is Safe to Eat?

There are several conditions to making sure sourdough bread is safe. Here we’ll go into detail about the specifics of sourdough bread, and why there is a concern over its bacterial content.

Sourdough Starter Contains Billions of Wild Bacteria and Yeast

The sourdough starter, which is the raising agent used in sourdough bread, not only contains billions of bacteria, but a really diverse range of bacteria too. It’s this combination of bacteria, along with different types of yeasts that give the bread its distinct developed flavor profile. The bacterial content found also differs from one starter to the next.

Here’s a list of common bacterial strains and yeast found in sourdough starters:

Types of Yeast Commonly found in Sourdough StarterTypes of Bacteria Commonly Found in Sourdough Starter
Saccharomyces diarensisLactobacillus brevis
S. exiguusL. plantarum
Candid milleriL. sanfranciscensis

It’s important to note that all of the above mentioned bacteria and yeast, and others that are found in healthy sourdough starters are not dangerous. In fact, these strains of bacteria and yeast are known now to be beneficial for the body. For more information, check out my article “Does Sourdough Contain Probiotics and is it Good for your Gut?”

As long as the sourdough starter is healthy, then these bacteria and yeast are completely safe to be used in bread and other recipes.

How Do I Know the Sourdough Starter is Healthy?

Making sure the sourdough starter is healthy is the secret to a good flavorsome sourdough bread, but it is also important for safety. If the sourdough starter does not have a strong enough population of good bacteria and yeast, it is possible for the starter to go bad.

Here are some signs of contamination in a sourdough starter:

  • Pink or orange tint or streak
  • Furry surface or dots of furry patches i.e. signs of mold
  • Blue/green moldy patches developing on the surface
  • No bubbles developing despite regular feedings

If any of the above are present in the sourdough starter, it is time to throw it out. These are all signs that the sourdough starter has developed dangerous bacteria and/or yeast that are not safe to consume.

It’s reassuring to know, that a sourdough starter gone bad is highly unlikely to make good bread in the first place, so the chances of eating a sourdough bread that has gone bad are minimal.

Sourdough Bread is Mold Resistant

The diverse ecosystem of bacteria and yeast found in sourdough bread actually give the bread mold resistant properties, which perhaps makes it even safer to eat than conventional shop bought bread!

Sourdough Starter has an Acidic Environment Resistant to Bad Bugs

Sourdough starter has a very acidic environment, mainly due to lactic acid produced as a byproduct from the starter. This acidic environment makes it extremely difficult for harmful bacteria to develop, hence making sourdough bread pretty safe.

Normal Behaviour in a Sourdough Starter

Bakers that are new to sourdough starter often worry that their starter has gone bad when they see certain common characteristics in their starter such as:

  • Liquid developing at the top of their starter – This liquid ranges from clear, to gray, brown or even black. This is known as hooch, and is very normal to develop in a sourdough starter every now and then.
  • Very pungent smell – Sourdough starter can develop a range of different smells, from vinegar like, to nail polish. It is common for new bakers to worry about the smell, but it is completely normal for sourdough starter to have very pungent smell that changes on a daily and even hourly basis.

Bacteria in Sourdough Bread Die When it is Baked

The bacteria and yeast that are present in the dough, are baked at high temperatures before you actually eat it as bread. The normal temperature for bacteria to die is a cooking temperature of above 140F (60C). Sourdough Bread is normally baked at around 420F (215C), which is more than enough to kill off any harmful bacteria that may be present in the bread.

Basic Food Hygiene Practices When Making Sourdough Bread

It goes without saying that basic food hygiene practices must be observed whenever baking or cooking at home. This includes:

  • Washing hands before handling food and food preparation equipment
  • Using clean utensils, equipment and cooking surfaces
  • Using ingredients within their use-by dates

In conclusion, sourdough bread is safe, if not safer than other breads to eat. Allergies and food intolerances set aside, there is no need to be worried about the bacterial content in sourdough bread, because even if bad bacteria did make it into the dough, it will most likely die at the cooking stage and be perfectly safe to eat. And if the sourdough starter has gone bad, it’s not likely to leaven the dough and turn it into bread anyway.

For more information about the health benefits of sourdough bread, read my article “Is Sourdough Bread Good for you? 7 Things you need to Know”.

Maintaining a Healthy Sourdough Starter

Maintaining a healthy sourdough starter is important not only to get good bread results, but also to make sure that the good bacteria and yeast are large enough in number to keep bad bacteria out.

Here’s a quick guide to keeping your starter healthy, bubbly and active.

Feeding the starter

  1. Feed your starter once a day, at roughly the same time every day.
  2. Use the same flour for your starter every feeding, as this is what it is used to!
  3. Your starter needs to be fed equal amounts of water and flour (by weight).
  4. Roughly feed your starter half its volume. (e.g. if you have half a cup of starter, feed it ¼ cup flour and ¼ cup water, which makes ½ a cup in total)
  5. It’s preferable to weigh your flour and water so that you are keeping its hydration level accurate to 100%. This is important when using in recipes.
  6. Use a plastic, silicone, or wooden spoon when mixing the starter, and give it a vigorous mix to allow lots of air to go into it.
  7. Make sure there is always plenty of empty space at the top of the jar. Your starter will ‘breath’ when it is being fed, so it will rise and then come back down again. If you haven’t left enough space for this, you will have a very big mess in a couple of hours!

For more information about maintaining sourdough starter check out my articles “Is my Sourdough Starter the Right Consistency?” and “When to Use Sourdough Starter at its Peak to Bake Good Bread”

Where to Keep your Starter

Starter should be kept in a glass jar, in a dark place, with enough room in the jar for the starter to rise and deflate.

You can either:

  1. keep it on your kitchen countertop in an opaque glass/ceramic jar with a loose lid on it
  2. keep it in a cupboard in a clear glass jar with a loose lid on it.

Starter should not be kept in steel, aluminium, wood, or other materials, as it has an acidic nature, and is not suitable to be kept in containers that can react with the acid. Glass or ceramic is best.

Is it Safer to keep Sourdough Starter in the Fridge?

If you’re using your sourdough starter regularly, it is best to keep it on the countertop in a warm area. This will keep the ecosystem of wild bacteria and yeast at a comfortable temperature to continue growing and keeping bad bacteria out. Sourdough starter should only be kept in the fridge if it is not going to be used regularly.

Related Questions

Is store bought sourdough bread safer than homemade?

Homemade sourdough bread is perfectly safe to eat, and the advantage of homemade is that all the ingredients are known. Store bought sourdough bread very often is not real sourdough, and may contain chemicals and food additives to preserve its shelf life. Store bought sourdough is not necessarily any safer to eat than a homemade sourdough bread. Check out our online courses to learn how to make your own sourdough bread.

Is sourdough bread safe for celiacs?

Sourdough bread is NOT safe for celiacs because it still contains wheat and gluten. But many people who are GLUTEN INTOLERANT find that they are able to consume sourdough bread without suffering from symptoms associated with gluten intake.

Aysha

I've been baking sourdough bread at home for years now and have had a journey full of successes and failures. This has given me great experience in understanding what makes a good bake!

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