Portonovo Wild Mussels

A mosciolo is Mytilus galloprovincialis: the same species as the mussel in every fishmonger's window. Nothing about the animal is different. What is different is that nobody farmed it.

Farmed mussels start as seed, get packed into mesh socks and hang from longlines in sheltered water, growing suspended, unbattered and constantly fed. Moscioli attach themselves to limestone rock beneath the Conero cliffs, anywhere from the surface down to seven or eight metres, and stay there for two or three years taking every storm the Adriatic sends.

That life is legible in the shell: thick, rough, brown-black, densely ridged, usually crusted with lime and small organisms, because it grew slowly and had to hold on. The meat yield is low: a kilo of moscioli gives under 200 grams of meat, against 300 or more for farmed mussels, and the meat itself is small, firm and deep orange rather than pale cream.

The bed is finite by definition: it is as big as the rock. Harvesting is regulated, the Slow Food Presidium dates from 2004, and a whole season is measured in tens of tonnes.

Salt first, then iodine, then a mineral, almost metallic depth that farmed mussels simply do not have. If a farmed mussel tastes of the sea in a gentle way, a mosciolo tastes of the sea the way an oyster does: bracing, and clearly from somewhere.

The texture is the second surprise. The meat is dense and slightly chewy, closer to a clam than to the soft plumpness of a rope-grown mussel, and it holds its shape in a hot pan instead of shrinking into a pale scrap.

The liquor they release is concentrated enough to season a plate of pasta on its own, which is exactly how Ancona uses it. Do not salt anything until you have tasted that liquid.

They are also less sweet than farmed mussels. Nobody eats a bowl of moscioli and thinks of butter; the register is bitter sea and stone.

Take away, do not add. Moscioli are salty, iodine-rich and already flavoured; anything assertive simply buries them.

The Ancona baseline is alla marinara: a wide pan, olive oil, a crushed garlic clove, a grind of black pepper, lid on, and off the heat the moment they open. The liquor they release is the sauce: strain it and dress spaghetti with it, with parsley and nothing else. Tomato is allowed in tiny quantities, two cherry tomatoes rather than a sauce.

The local speciality is in porchetta, which in the Marche means cooked with wild fennel and garlic, often with a handful of breadcrumbs. It is the same seasoning the region uses for rabbit and for stockfish, and it works because fennel can stand up to iodine.

Two rules of timing. Moscioli are tougher than farmed mussels and want an extra minute; one minute past that and they turn to rubber, so stand at the pan. And never salt the dish before tasting the liquor: it is usually salty enough on its own.

Raw with lemon is a genuine Ancona tradition, but raw bivalves remain the commonest vehicle for hepatitis A and norovirus. Purification reduces the risk without removing it, so treat it as an informed choice, and skip it entirely if you are pregnant, elderly or immunocompromised.

They are bought live and cooked live, which makes this a matter of hours rather than days. Keep them in the least cold part of the fridge, in an open container so air reaches them, under a damp cloth. Never in fresh water, which kills them within half an hour, and never sealed inside a plastic bag. The usual span is twenty four hours from purchase, forty eight at the outside, and the dispatch centre label carries the date. Clean them shortly before cooking: pull the byssus towards the pointed end, scrape the shell and rinse under cold running water, without soaking, which waterlogs the flesh.

Standard practice before the pan is to set aside any with broken shells and any that stay open when you tap them, and after cooking to set aside any that stayed shut. Once cooked, they keep a day or two in the fridge, shelled and covered with their own filtered liquid, which stops the flesh drying and turning tough. Cooked and shelled they freeze for a couple of months. Raw they do not, because freezing forces the shells open and the flesh thaws stringy.

The shell tells the whole story. A mosciolo has a thick, rough shell, blue black tending to brown, with dense irregular growth lines and almost always some encrustation, because it grew clamped to a rock and fought the sea for years. A rope grown mussel has a thin, smooth, glossy, regular shell, since it hung suspended and never touched anything. The size is smaller and uneven too: in a crate of moscioli no two are identical, while farmed ropes give graded shellfish that look stamped out.

Cooking settles it. The wild flesh is compact and deep orange, sits in one corner of the shell and never fills it; the farmed one is bigger, paler, softer and fills the valve. Weigh them and the gap is obvious: three kilos of moscioli give roughly six hundred grams of meat, three kilos of farmed mussels almost double. Two checks at the counter. The dispatch centre label has to state where they were harvested, and if the Conero does not appear on it they are not Portonovo moscioli. And the price: in season, below about eight euros a kilo, the arithmetic does not work.

Realistically, in the Marche and nowhere else. The animals are sold alive, the season is short and the annual catch is tiny, so moscioli do not travel: outside Italy they are effectively unobtainable, and any UK or US supplier advertising them is almost certainly selling farmed mussels under a regional name.

In Italy, buy them between May and September at the Ancona fish market, at fishmongers in Ancona, Portonovo, Sirolo and Numana, or direct from the divers where local rules allow. Expect 10 to 18 euros per kilo (roughly 5 to 9 dollars per pound, or 9 to 16 pounds per kilo), against 3 to 6 euros for farmed mussels.

Check the label that must accompany all live bivalves: it states the species, the harvesting area and the date. If the area is not the Conero coast, they are not moscioli di Portonovo. If they are on sale in January, they are not moscioli at all.

Buy them the day you cook them, keep them in the fridge under a damp cloth, never in fresh water and never sealed in plastic, and discard any that do not close when tapped.

Portonovo itself: a bay reached by a single hairpin road, with a Romanesque church, a Napoleonic fort, two brackish lagoons behind a white pebble beach, and a row of former fishermen's huts on the water that are now restaurants. Access by car is restricted in high season, so check before driving down.

The wild mussel festival in early September is the single best day for it: the whole repertoire cooked at once, with the divers on the quay. Sirolo and Numana, a few kilometres south, serve the same food with more beach.

In Ancona, the trattorie around the port and the old town cook moscioli alongside the city's other great dish, stoccafisso all'anconetana, a long-braised stockfish stew. The Mercato delle Erbe is where to look at them raw before ordering them cooked. The whole coast sits inside the Conero regional park, which is worth a walk between lunches.