Understanding sourdough

Let’s face it, sourdough tastes great. It’s a popular choice and it seems to be what most cafes are using as part of their breakfast meals and toasties. Sourdough is also commonly known as being lower glycaemic index (GI) and better for digestion. But have you ever wondered why this is? In this article we are going to unpack sourdough bread and help you differentiate between an authentic, traditional sourdough and those that are faking it.

What is sourdough?

Sourdough is a type of bread made through natural fermentation using wild yeast and bacteria. Sourdough doesn’t require commercial baker’s yeast, instead it uses something known as a sourdough starter. A sourdough starter is simply made from a mixture of flour and water that is fermented over time. The sourdough starter is what allows the bread to rise. Not all bread labelled sourdough is authentic sourdough. Many store bought “sourdough” breads are just white bread with added vinegar (to create a sour flavour) and commercial yeast.

How to tell if it’s real sourdough

Check the ingredients list
Authentic sourdough has 4 core ingredients:

- Flour
- Water
- Salt
- Sourdough starter

Avoid “sourdough” breads with:

- Yeast (instant, baker’s yeast)
- Additives like vinegar, emulsifiers, softeners or preservatives
Look at the texture
Authentic sourdough is usually light and airy (often with holes in it), has a thick chewy crust and often an irregular shape – think “rustic”. Fake sourdough tends to have a softer crust and a more perfect shape.
Smell and taste
Real sourdough has a slightly tangy taste and fermented smell. Fake sourdough may just taste like regular bread with a hint of sourness.
Buy from the right place
The best chance at finding authentic sourdough is from an independent Artisan bakery or farmer’s market. At the supermarket, look for labels like “naturally leavened”, “long fermented” or “no added yeast”. Majority (if not all) loaves on the supermarket shelves will not be authentic sourdough.

What are the benefits of authentic sourdough?

Easier to digest: the long fermentation process breaks down gluten and starches, making the bread easier to digest. Some people with gluten sensitivity (not coeliac disease) experience less digestive upset when eating sourdough bread in comparison to regular bread.

Lower GI: sourdough has a lower GI than most white breads. This is due to the acids that are produced during fermentation which slow down carbohydrate digestion (providing a slow steady rise in glucose levels, rather than a spike). A sourdough with added wholegrains will be lower GI than white sourdough because it contains more fibre.

Less preservatives: the acidity from fermentation naturally preserves the bread, removing the need for additives and preservatives.

NOTE– all types of sourdough are still a source of carbohydrate, which means they will affect glucose levels. Often the size of a sourdough slice served in a cafe or when cutting it yourself is larger and thicker than a traditional sandwich slice of bread. This leads to a higher carbohydrate load and higher rise in glucose levels after the meal - so portion size is important for sourdough bread as it is for all low GI carbohydrates foods.

Which is the best bread to choose?

Ultimately, the best bread for our health is one that is densely packed with wholegrains. This type of bread offers the most fibre and B vitamins, more protein and less carbohydrate per serve. Which also makes it the best choice for blood glucose levels.

An authentic sourdough may also be a good choice for people with sensitivity to gluten (not coeliac disease) or other digestive concerns.
If you do choose sourdough, use the tips above to make sure it’s authentic and even better, choose one with added seeds or wholegrains (like linseeds, pumpkin seeds or sunflower seeds).