Sourdough is one of the oldest forms of bread and dates back to ancient Egypt. Unlike most modern breads, sourdough uses wild yeasts to rise. These wild yeasts are all around us and vary according to our location. You can create your own natural sourdough starter just by using flour, water and these yeasts.
If looked after correctly your starter will provide you with the fantastic reward of your own sourdough loaves for years to come.
The starter uses a combination of bacteria and wild yeasts to create the right environment for both to grow. The yeasts in the dough produce carbon dioxide that becomes trapped in air pockets in the bread (causing the bread to rise). The yeasts also produce ethanol which the bacteria feed on to produce lactic acid and acetic acid (causing the slightly sour taste), which is good for the yeast but inhospitable to other organisms. The dough also needs stretchy gluten so it can catch the carbon dioxide produced by the microbes.