The Margherita Pizza Chef Course Module 1 – The origins 2) The grinding

The wheat grinding Below the structure and functioning of the mill since its origin is described : water and wind mills; steam and electric mills and the modern mill; and finally, the steps of the grinding process of wheat and its products.

The mill The mill is a milling plant to grind cereals and produce flour. Note: the term mill derives from the word “mola", a stone used in ancient mills.

The mill A mill can be driven by different forces: in ancient times, human and animal forces were generally used. Indeed, among the ancient peoples (the Egyptians, the Greeks and the Romans) the mills were moved mainly by animals but also by human beings (slaves, prisoners, poor citizens).

Watermills and windmills The mill can be of two types: watermill and windmill. Both mills provide for the movement of a blade wheel that is activated using the force of water or wind.

The watermill The watermill in Europe precedes the use of the windmill. The watermill was invented in the ancient Mesopotamia (the so- called fertile Crescent), where it would have been used since the Sumerian times (4000 BC). It would have been introduced following the use of the cone grinder: the wheels of these mills could be both vertical or horizontal.

The watermill The watermill spread in medieval Europe from 800 AD.

The watermill The medieval flatland towns, rich of bridges and canals, over time became the ideal venues for the spread of numerous watermills all over Europe.

The watermill The type of mills was mainly due to the nature of the water courses that fed them. If the river had a significant and constant water flow, it was possible to place the structure of the mill just at surface-level.

The watermill The wheels of these heavy structures were generally made of oak wood and iron, composed of some dozens of blades and lying on lead-coated supports.

The watermill Also their large transmission shafts were made of oak wood and were held by leaded supports, while other gears were made of elm wood. Their teeth were twisted into the wheels.

The watermill A large central shaft moved the upper grinding mill, which was contained along with the lower bottom, in a big box.

The windmill The windmill, in turn, is a structure built to transform wind energy into mechanical energy for various purposes (agricultural, crafts, etc.). The windmill originated in ancient Persia (today Iran) in 600 AD and was then introduced to Europe in 1100 AD, where it spread widely .

The windmill The European windmills over time became bigger and more complex, used by their owners for various purposes: grinding flour and salt, squeezing oils, activating sawmills. Every owner of a building, built his own mill for a specific function. They spread mainly in the Netherlands and England. Currently around a thousand windmills are active in the Netherlands; Amsterdam has eight.

Steam and electric mills Since the 1920s the first steam mills were used. Between the 1800s and the 1900s, the mill benefited from several technical innovations: the use of alternative energies to water and wind, such as steam and electricity; the construction of parts of the cast using iron and steel to replace the wood; the use of quartz grinders, tougher and more durable than previous ones; the increase in milling speed.

Steam and electric mills With the advent of cylinder mills, in the 1800s, the corn was no longer crushed, but passed through pairs of rotating rollers made of iron.

Steam and electric mills In this way, a more refined grinding product was obtained through: - the reduction of the overheating of flours and hence their deterioration, - the elimination, after several passages, of the wheat bran.

Steam and electric mills A very fine grinding product was the white bread, which even being poor in nutrition, represented a social status symbol until the second half of the 1900s, when its consumption began to decline in the face of the acquired knowledge of nutritional properties of food.

The current mills - industrial plant Due to the use of electricity since the 1950s, in today's food industry the mill is considered as a complex, highly technological industrial plant for the processing of grain and flour.

The current mills – high technology Contemporary mills are organized in three distinct sections: - Wheat stocks are stored in the silos, periodically ventilated to avoid mold formation. - In the grinding room are allocated the mills that turn wheat into flour. - in the warehouse are stored the flour bags waiting to be shipped.

The current mill- the grinding The grinding is done in the grinding room. Such operation is composed of three steps: - wheat rupture; sieving; re-grinding

The current mills – the wheat rupture The first operation is the rupture. Wheat comes from the silos and enters the grinding room. It is carried to the first machine where it is "broken" by two steel cylinders ridged with straight lines, each rotating in the opposite direction to the other.

The current mills – the sieving The second operation is the sieving. The ground wheat falls on a swinging sieve that holds the largest pieces (bran) and passes the smaller fragments, consisting of coarse flour blended with bran. Then the procedure is repeated in the other machines where the cylinders get closer and the sieves are finer.

The current mills – the re-grinding The third operation is that of the re- grinding, that ends the whole grinding process. The re-grinding is done by machines with cylindrical and very close rollers.

The current mills – the flours At the end of the process described, the products of the grinding are obtained: the different flours.