Parmigiano Reggiano

Parmigiano Reggiano is a hard, cooked, slowly ripened cheese made from raw cow's milk: evening milk left to let the cream rise, skimmed and combined with whole morning milk in copper vats. There are no additives, no preservatives and no colourings: only milk, salt and natural calf rennet. That purity is why the specification bans silage and any fermented feed from the cows' diet.

A wheel weighs at least 30 kilos and usually 38 to 40, and takes around 550 litres of milk, roughly sixteen litres for every kilo of finished cheese. Minimum ageing is twelve months, but the standard commercial ages are 24, 30 and 36 months.

The zone has not changed in centuries: the provinces of Parma, Reggio Emilia and Modena in full, the part of Bologna west of the Reno river and the part of Mantua south of the Po. Boccaccio described it in the Decameron in 1349, in a passage about a mountain of grated parmigiano used to dress pasta.

Savoury depth first: the flavour scientists call umami, and Parmigiano has more free glutamate than almost any other food. Underneath that sit brown butter, toasted hazelnut, dried pineapple and a long beef-broth finish. Salt is present but restrained, around 1.4%, which surprises people who arrive expecting Pecorino-level intensity.

The texture is hard, dry and granular, splitting into irregular shards rather than slicing, and from eighteen months onwards it is dotted with crunchy white tyrosine crystals that read as tiny bursts of savoury crunch.

Age changes it substantially. Twelve to eighteen months is milky, yoghurt-tangy and comparatively soft. Twenty-four is the balanced classic. Thirty and thirty-six are drier, spicier and fruitier. Past forty months it becomes crumbly and almost peppery, a cheese for tasting rather than grating.

Buy a wedge with the rind on and grate to order. Pre-grated Parmigiano loses most of its aroma within days of opening, and the pre-grated tubs sold as 'Parmesan' abroad are frequently a different cheese entirely.

Use 12 to 18 months for shaving raw over salads, carpaccio and vegetables. Use 24 months for cooking: grated over tagliatelle, stirred into risotto at the mantecatura, folded into pasta fillings, whisked into a crema di parmigiano. For that cream, heat milk or cream to about 80°C, take it off the heat and stir in the grated cheese, because boiling makes it split.

From 30 months upwards, stop cooking with it. Break it into irregular shards with an almond-shaped knife and serve it with traditional balsamic vinegar, honey, pears and walnuts.

Save every rind. Scraped clean and dropped into minestrone or a bean soup, it releases flavour for an hour and is good to eat afterwards.

A vacuum pack keeps in the fridge at 4 to 8 C until the date on the label. Once it is open, wrap the wedge in a barely damp cloth and then in greaseproof paper, or keep it in a rigid box that is not airtight. Cling film laid straight against the cheese makes it sweat and a wet sheen builds on the surface inside a week. A piece that still has its rind holds around three months at fridge temperature.

What changes over those months is water. The cut face dries, goes glassy and darkens at the edge, and that skin comes away with a scrape of the knife before you use the rest. Dry bloom on the rind itself lifts with a cloth dipped in vinegar; anything else on the surface is a question for the shop that sold it and for the date on the pack. It freezes in 200 to 300 g portions for about six months and comes back more crumbly, which is why thawed pieces are better grated than served in shards. Rinds, scraped clean, sit in the freezer indefinitely and go into soup.

Everything you need is pressed and burned into the rind. Around the whole heel the words PARMIGIANO-REGGIANO appear in pin dots, repeated over and over, alongside the month and year of production, the registration number of the dairy, a casein plaque carrying the unique code of that wheel, and the oval fire brand added only after the inspection at twelve months. On a wedge cut abroad you should still see a stretch of that dotted rind: a rindless block, or a rind with nothing on it, is another cheese. Ask the counter for the age in months rather than accepting the word aged.

The paste is straw yellow and breaks into granular flakes instead of slicing clean, with white tyrosine crystals plainly visible from eighteen months. It should smell of melted butter, nuts and meat broth. What it gets confused with abroad is the word parmesan, which outside the EU and the UK is generic: the shaker tubs and pre-grated bags are usually domestic hard cheese with cellulose added to stop it caking. Grana Padano is the honest relative, milder and clearly cheaper.

In the US, Costco, Whole Foods, Wegmans, Eataly and Italian delis all carry it, at roughly $18-30 per pound depending on age. Costco's Kirkland wedge is genuine DOP and is usually the best value in the country. Avoid anything labelled simply 'Parmesan' or 'Parmesan cheese': in the US that is a generic name and means nothing about origin.

In the UK, all major supermarkets carry it at about £22-40 per kilo, and 'Parmesan' on a UK label legally means Parmigiano Reggiano.

The rind carries the entire identity: dotted pin writing reading PARMIGIANO-REGGIANO all around the heel, the month and year of production, the dairy's registration number, a casein plate with the wheel's unique code, and an oval fire brand applied only after the twelve-month hammer inspection. Wheels that failed inspection have those marks stripped or scored with parallel grooves.

Ask for the exact age rather than accepting 'aged'. Two labels worth paying more for: Prodotto di Montagna, from mountain dairies above 600 metres, and Vacche Rosse, made from the milk of the Reggiana red breed alone and aged at least twenty-four months.

The dairies themselves. Around fifty caseifici across Parma, Reggio Emilia and Modena take visitors in the early morning, when the curd is broken at about half past six. The local tourist consortia handle bookings, and a visit usually ends with a tasting of three different ages.

The Museo del Parmigiano Reggiano at Soragna, in the province of Parma, sits inside a nineteenth-century dairy. Bibbiano, in the Reggio hills, claims to be the cheese's birthplace and its cooperative dairy is a standard stop.

In September the Caseifici Aperti weekends open the whole zone to free visits. And in the covered markets of Parma and Modena you can taste twelve, twenty-four, thirty-six and sixty months in sequence at a single counter, which teaches more in ten minutes than any amount of reading.