Making sourdough involves mixing wheat and/or rye flour with water into a loose dough, which is then left to rise. Lactic acid, acetic acid and aromatic compounds of natural microorganisms called acid bacteria form in the sourdough.
Baking with sourdough has a number of advantages. The bread is moister, stays fresh for longer, is less crumbly, has a better texture and a richer aroma and acidic taste. The bread is also less sensitive to mould.