Sourdough is a natural fermenting substance consisting of water, flour and various microorganisms. The type of flour, microbial flora and different processing methods lead to the creation of sourdough, each of which creates unique characteristics in bread. Microorganisms in sourdough use the starch and minerals in flour to ferment and increase the volume of bread, and the by-products of their activity, which include various organic compounds, are the cause of aroma and taste.