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What is sourdough?

Updated: Dec 2, 2020

We hear the word "sourdough" being used in so many bakeries but what does it really mean? We hope you will have a better understanding after reading this article.


Sourdough breads have been around for a long time. There has been evidence that sourdough breads existed 4500 years ago in Egypt. Scientists have even found traces of sourdough cultures in excavated pottery. You can read more about it here.

To generalize, sourdough breads are leavened by lactic acid bacteria and wild yeast (also known as sourdough starters). These organisms can be found all round us. It is important to understand that not all bacteria are detrimental to our health. Kimchi, cheese and yogurt are great examples of food that goes through a similar process of fermentation. You may have heard of the benefits of "probiotics" attached to yogurt or supplements. Probiotics are just a classification of living bacteria that are deemed beneficial for your gut.


In the world of baked goods, flour naturally contains a variety of yeasts and bacterial spores. When we create a "starter", we are basically creating a thriving environment for the lactic acid bacteria and wild yeast. In the simplest of terms, a sourdough starter is what helps make bread rise. But let's dive a little deeper to see what's really happening.

Lactic Acid Bacteria

The bacterias work in a mutually beneficial relationship with the wild yeast. By consuming maltose sugars, the bacteria release lactic and acetic acid which lowers the pH of the starter. That is where the sour tangy flavor comes from when you're eating that slab of avocado toast. An acidic environment results in a space where it is difficult for harmful bacteria to grow. As a result, the bacteria is actually helping preserve your bread without adding any artificial preservatives!

Wild Yeast

We talked about how acidic environments makes it difficult for microbes to grow. Fortunately, the strain of wild yeast in sourdough starters are able to survive in a low pH environment. Carbohydrates, glucose and fructose are the main food source for yeast molecules. As the carbohydrates are being broken down, the yeast molecules release CO2 and ethanol. It is this reaction that helps a properly mixed bread dough rise in the oven.

When we incorporate a sourdough starter into our bread recipes, this entire reaction takes place during the fermentation process. In the end, your bread is easier to digest while having a unique depth of flavor.


Growing up in an Asian background, I was never really exposed to the world of bread. Even when I was eating sourdough bread, I still didn't fully appreciate it. I only realized how good it was when I had to revert back to generic supermarket bread. If I wasn't too lazy, I could have made my own. If you have good bread during a meal, it is just so much more satisfying. The best breads can be eaten on its own without butter or dips. Once you've eaten a loaf of sourdough bread, you'll notice a world of difference.

On a side note, be cautious of "sourdough" bread that you can find at the grocery store. There are some manufacturers who add "sourdough flavor" as an ingredient in the loaf. This is not sourdough bread. Don't fall for their marketing tricks.

For more a more in depth explanation of how a sourdough starter works, check out a great article posted by The Modernist Cuisine.


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