What is sourdough, and why should you eat sourdough bread?

It's the go-to ingredient for artisan bakers, but what is sourdough and why does it make the best bread?

Sourdough bread is becoming more and more popular, and it’s not difficult to understand why; it’s flavourful, keeps well, and is more nutritious than standard bread.

Sourdough is believed to have been discovered several thousand years ago, and was the main method used to make bread rise until well into the middle ages. It was gradually replaced, first by the use of barm left over from beer making, then using cultured yeasts.

Now, though, with the growth of artisan baking, sourdough has once again become a major player in the world of bread. But what exactly is it, and is sourdough really better for you than other breads?

So what exactly is sourdough?

Sourdough is a name for a mixture of water and cereal flour containing a culture of naturally occurring yeasts and lactic acid bacteria. It is often also used to name breads made using such a culture.

Yeasts and bacteria suitable for bread production are found in relatively high amounts on the surface of cereal grains, such as wheat. By grinding the grains into flour and allowing these micro-organisms to thrive - by adding water, keeping the mix at an appropriate temperature, and providing food in the form of more flour to create what is known as a ‘starter’ - they can be increased in size and concentration.

Sourdough starter.

Eventually there will be enough yeast cells giving off carbon dioxide to make bread rise. The interaction of the yeast and the natural enzymes they secrete will have a beneficial effect on the flavour, texture and aroma of the bread they go to make.

What are the benefits of sourdough bread?

Genuine sourdough bread should take longer to go stale, and has some health benefits.

Lactic acids make the vitamins and minerals in the flour more available to the body. The acids slow down the rate at which glucose is released into the blood-stream and lower the bread's glycaemic index. They also make the gluten in flour more digestible.  Sourdough bread also contains higher levels of folate and antioxidants than other breads.

So are all sourdough breads good for you?

Some store-bought sourdough breads are not made using the traditional sourdough method, thereby reducing their health benefits.

The Real Bread Campaign says that to called sourdough, a bread can only be made using a live sourdough culture, not inactive dried sourdough powder added purely for taste and acidity; without the addition of commercial yeast or other leavening agents (e.g. baking powder); without any artificial additives; and without using other ingredients as souring agents.

How can I be sure I’m buying proper sourdough bread?

First, always read the label. Genuine sourdough is made with just flour, water, salt and perhaps other natural ingredients. If baker’s yeast (usually listed simply as yeast), sourdough powder or anything else is present, then it’s not true sourdough.

If possible, ask for a sample to check the taste, texture and aroma. A well-made, genuine sourdough should have an almost glossy inside with big holes, a crackling crust that becomes chewy; and a complex, delicious taste and aroma.

Sour bread sounds odd – I’m not sure I’ll like it…

The sourness of sourdough bread is entirely down to the baker’s preference, and can range from an almost imperceptible flavour to a strong tang. A baker controls his or her starter culture in order to get not only depth and complexity of flavour but also a level of acidity that is to his or her taste.

If you've tried sourdough from one baker and not particularly enjoyed it, try a loaf from a different one.  As no two are exactly alike, you might find you like it.

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