With milk, rennet and fire

The question, "how is Parmigiano-Reggiano made?" begins with "where and when" because the product is circumscribed by precise territorial limits as well as seasonal limitations.

Production is exclusive to the "zona tipica", which includes the provinces of Parma, Reggio Emilia, and Modena in their entirety: Mantua on the right bank of the Po river and Bologna on the left bank of the Reno river. The working season begins on April 1 and ends on November 11. The work is done in a cheese dairy or "casello". This is as a rule a small building, where on the average about four to ten cheeses are turned out daily. Although traditional methods are used, the organisation and equipment are completely up to date and in line with the highest standards of modern hygiene. The milk arrives from the neighbouring farms in a constant flow. Its exceptional qualities derive both from environmental factors and from the special milking habits of the heifers, which are reared with great care and nourished predominantly with fresh fodder. Two successive milkings are used in each batch of cheese: the evening's milk is poured out into small trays to rest throughout the night; the morning's milk is used after it has rested for about one hour.
A proportion of the naturally accumulated cream is skimmed off; the evening and morning milks are then poured together into a copper kettle shaped like an inverted church bell. At this stage, the "starter" or fermenting-whey is added.
This whey is a residue of the preceeding batch in which the lactic flora has developed by fermentation. This practice, which is ancient, raises the acid content of the milk to bring about the correct degree of fermentation in the cheese. For this purpose the milk is heated in the kettle to a temperature of 33° centigrade, while stlirring slowly. The heat is then turned offand the rennet - a natural extract from the stomach of sucking calves - is added to the milk. Coagulation occurs within 12 to 15 minutes. In the coagulated milk or curd ("cagliata") the most nutritive elements are made available in solid form by the action of the rennet: the liquid that remains is known as whey.  The curd is turned over and broken up with a sharpedged tool known as the "spino" (thorn-bush). This operation reduces the coagulated mass to fragments the size of' wheatgrains, ready for the "cooking". Over a slow heat the temperature of the curd is raised to 45° then the heat is stepped up sharply until the mass reaches a temperature of 55° centigrade.
When the heat is turned off, the cheese-granules are precipitated towards the bottom of the kettle where they again form a solid mass. After about half an hour this mass is raised with a wooden paddle, collected in a hempen sieve-cloth and then taken out.