A sourdough is a mix of flour, water and natural yeast cells living in the flour and in the air. This mixture is left to ferment, and when it is sufficiently active and filled with bubbles of gas, it can be used to leaven bread.
Every day, we use our sourdough as an ingredient in all of our breads. We always make sure we have some left at the end of the morning. We refresh this with more water and more flour, and by the next morning, the yeast cells have reproduced in sufficient numbers that the mixture is full of bubbles and is ready for us to bake with again. The sourdough is therefore constantly perpetuated. Some bakeries in Northern Europe have sourdough cultures that are generations old; ours is only twelve years old so far!
Our main sourdough is made from white flour, but we also have a spelt sourdough for our spelt bread, and a rye sourdough for rye breads.
The French term for sourdough is levain, so we often refer to our sourdough loaves in this way, such as a spelt levain, or a wholewheat levain.
Why use a sourdough?
Using a sourdough culture to leaven bread has some fantastic advantages. A sourdough is naturally acidic, as it produces organic acids and ethers as it ferments. This increases the acidity of the final loaf, which has a number of effects.
Firstly, this naturally lengthens the shelf life of the bread without using artificial preservatives.
Secondly, it strengthens the gluten structure, therefore allowing us to make a wetter, looser dough, resulting in a final loaf that is more moist.
Thirdly, the acidity developed during a long fermentation and proof improves the flavour of the dough.
Fourthly, the use of a sourdough culture encourages our body to extract more of the minerals and goodness from the flour as we digest the bread.
All in all, using a sourdough is a great idea!