Max Latouche is the talmelier (baker) of the construction site of the medieval castle of Guédelon. Installed in the courtyard of the fortress, he explains to the visitors how sourdough bread was made in the Middle Ages. At that time, cereals called bleds formed the basis of the diet of European populations and were eaten in the form of bread, pancakes, and porridge. The bread of the poor was a black bread made from meslin (wheat and rye) as well as barley and barely sifted wheat flour. Whiter, the bread of the rich was made with finely sifted wheat. The proliferation of watermills from the 11th century enabled the production of larger quantities of better quality flour.