What is a Sourdough Starter
A sourdough starter is how we cultivate the wild yeast in a form that we can use for baking. Since wild yeast are present in all flour, the easiest way to make a starter is simply by combining flour and water and letting it sit for several days.
Your starter is just flour and water – that’s it! That’s all your wild yeast needs to feed and grow. Your starter will live for many years given the right growing conditions and the right food.
Wild yeasts prefer slightly cooler temperatures to the manufactured yeasts we’re used to seeing, meaning the proofing stage of bread takes a lot longer.
How does a Sourdough Starter work?
Yeast is present on the surface of cereal (eg wheat, rye) grains. When those grains are crushed to flour, and that flour is then mixed with water, the yeast will begin to multiply and thrive. As the yeast feed on the flour, they produce carbon dioxide gas.
Over time, if more flour and water are provided, and the mixture is ‘refreshed’, the yeast colony will become more concentrated. Eventually, the mixture will produce enough gas that, on adding it to a dough, it will raise that dough to form bread.
Alongside yeast, bacteria also thrive in the mixture. Those which are beneficial to sourdough making, including lactic and acetic acid bacteria, will multiply well alongside the yeasts present.
These bacteria produce acids that contribute to the flavour and texture of sourdough breads. These acids may also help preserve breads made with the mixture, lengthening its shelf life.