Why Does My Bread Taste Sour?

Unless you’re making sourdough bread, the last thing you want is for your bread to taste sour – and even then, too much sourness isn’t always desired. So what happens if your loaf turns out with a sour flavor? What went wrong, and how can you avoid it next time?

There are multiple causes for bread tasting sour. The most significant reason is that you used too much yeast than you were supposed to. The other potential problem is that it fermented for too long. Less commonly, it can be an issue with stale yeast or underbaking.

Hey, there, bread lovers! My name’s Michelle, and I enjoy baking bread as much as I love eating it. Throughout my many years of experience, I’ve run across undesirably sour loaves. I’m here to share what went wrong and how to prevent it in the future.

Let’s get that sour taste out of your mouth!

Why is My Bread Sour? (4 Reasons)

There are actually four things that can cause your homemade bread to end up with a sour flavor. Knowing the cause can help you prevent it from happening in the future. (Being proactive is always the best thing to do – right?) 

That said, let’s take a look at the four primary reasons for sour bread.

1. Too Much Yeast

Yeast is like the creamy center of an Oreo – essential. And while making a loaf of bread sans yeast is possible with the help of another leavening agent, the typical go-to and recommended product is yeast.

But too much of anything is never a good thing, including yeast.

People may add more yeast than necessary for several reasons. For instance, they may want their bread dough to rise faster and think yeast is the key to speedy fermentation. Or, they simply added too much yeast by accident.

Whatever the reason, an excessive amount of yeast will cause a sour flavor. That’s because yeast produces lactic and acetic acids, generating a sour taste. 

2. Over-Proofing

Yes, yeast is vital to bread-baking success. But so is proofing. And over-proofing your dough can lead to many adverse side effects, such as collapsed loaves, bread that smells like alcohol, and, yes, bread that tastes sour.

Again, it all comes down to the yeast producing lactic and acetic acids during fermentation. Sure, some of these acids are critical for a beautiful and delicious loaf. However, too much acid will just lead to an abundantly sour flavor.

If you allow your dough to ferment for too long, you give the yeast plenty of time to continue producing lactic and acetic acids.

3. Stale Yeast

Stale or expired yeast should be avoided for two primary reasons. For one, stale yeast isn’t going to work as well as fresh, active yeast. That means you will have to allow the dough to proof for an extended period, which can lead to sourness.

The other issue is that stale yeast tends to have a sour flavor from the get-go; before it even enters your dough. If you’re starting with sour yeast, you can only expect one outcome: bread that tastes sour.

4. Under-Baking

Bread that isn’t fully cooked can lead to sour flavors alongside a strong alcoholic smell. Again, we have yeast to thank for that.

While your bread is baking, some of the sour, yeasty, and alcoholic flavors and scents are cooked out. If you don’t give your bread enough time in the oven, some excess acids and bacteria can hang around, causing a sour taste.

How to Prevent Bread That Tastes Sour

Bread that comes out of the oven with a sour flavor is pretty much a done deal. It’s up to you whether you want to consume it or not. However, you need to be extra careful with your next loaf. Here are a few ways to prevent bread that tastes sour.

1. Don’t Add Too Much Yeast

The simplest solution to prevent sour-tasting bread is not to add too much yeast. Always stick to the recipe – and not half a teaspoon more. To ensure you’re 100% accurate and won’t accidentally add too much yeast, consider purchasing and using a kitchen scale.

2. Don’t Over-Proof

I’ve said it once, and I’ll say it again – allowing your bread to proof is critical. Don’t try to get by without doing it. However, you should avoid going overboard. 

Most bread will proof between one and three hours at 75F, although some prefer to proof their bread in the refrigerator for up to 24 hours. While that’s perfectly fine, I don’t recommend extending the proofing period beyond 24 hours.

Also, you should keep an eye on your bread dough as it ferments. Once it has doubled in size and doesn’t spring back when touched, it’s ready to be baked.

3. Use Active Yeast

Did you know that you can perform a simple test to see if your yeast is active? All you need to do is add one teaspoon of sugar, an envelope of yeast (2 ¼ teaspoons), and ¼ cup of water to a cup or jar. If the yeast is active, it will produce bubbles and a yeasty scent after ten minutes.

If you find that your yeast is not active, toss it right away and purchase fresh. That way, you won’t have to worry about using stale, inactive yeast that can produce sourness.

4. Bake It For the Right Amount of Time

Every bread recipe is different, so it’s critical to follow it from the beginning to the end. That said, most bread will take less than an hour to bake. The key is to make sure the bread is baked fully. Using a bread machine can help cut down on the guesswork.

You can check the doneness of your bread by giving it a nice tap. If it sounds hollow, it’s baked and ready to be taken out of the oven. It should also have a nice, golden brown crust and be pulled away from the sides of the pan. 

Achieve more accuracy by using a bread-baking thermometer. Most bread is done when it reaches an internal temperature of 190F, although certain bread types – like those with butter and eggs – need to reach 200F. 


At this point, you know why your bread ended up with a sour flavor. More importantly, you know how to prevent it from happening again. If you’re still an eager beaver looking to learn more info, I have a few interesting questions you might want to read.

How do you get the sour taste out of bread?

Once it’s done baking, there is not much you can do besides grit your teeth and eat it or toss it and start from scratch. However, you can play around with sourdough bread and adjust the sourness before throwing it into your oven or bread machine.

If you want to have a tamer sour flavor in your sourdough, here are a few suggestions: add some baking soda to neutralize the acids, use white flour instead of wheat flour, get rid of hooch on your sourdough starter, don’t de-gas, and opt for a slower, warmer fermentation.

Can you eat sour-smelling bread?

It should be perfectly fine to consume, as long as there are no other indicators that the bread is unsafe to eat – for instance, it has mold, tastes odd beyond the sourness, or is as hard as a rock. 

Bread Can Taste Sour for Many Reasons!

Needless to say, bread can end up with a sour flavor for many reasons, but the most prominent reason is that you used too much yeast. Always make sure you follow your bread recipe closely to avoid overwhelmingly sour results.

Have you ever baked bread that turned out sour? How did you prevent it? Do you have any tips or tricks to share?

About Michelle
I have been a lover of sweets since day one. This led me on a self-taught baking journey starting at the age of 13. It's been over 10 years since the start of my baking adventures, and I’ve learned a lot along the way. Now, people rave about my delectable treats, whether it’s a chocolate cake or a strawberry crepe.

Leave a Reply

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

  • Beverly

    Thank you for this post. I can’t wait to try less yeast, just-right proofing time and full baking time to see if my bread improves. 🙂