Casu marzu

Fermentation

Casu marzu is created by leaving whole pecorino cheeses outside with part of the rind removed to allow the eggs of the cheese fly Piophila casei to be laid in the cheese. A female P. casei can lay more than 500 eggs at one time. The eggs hatch and the larvae begin to eat through the cheese. The acid from the maggots' digestive system breaks down the cheese's fats, making the texture of the cheese very soft; by the time it is ready for consumption, a typical casu marzu will contain thousands of these maggots.

Consumption

Casu marzu is considered by Sardinian aficionados to be unsafe to eat when the maggots in the cheese have died. Because of this, only cheese in which the maggots are still alive is usually eaten, although allowances are made for cheese that has been refrigerated, which results in the maggots being killed. When the cheese has fermented enough, it is often cut into thin strips and spread on moistened Sardinian flatbread (pane carasau), to be served with a strong red wine like cannonau. Casu marzu is believed to be an aphrodisiac by Sardinians. Because the larvae in the cheese can launch themselves for distances up to 15 centimetres (6 in) when disturbed, diners hold their hands above the sandwich to prevent the maggots from leaping. Some who eat the cheese prefer not to ingest the maggots. Those who do not wish to eat them place the cheese in a sealed paper bag. The maggots, starved for oxygen, writhe and jump in the bag, creating a "pitter-patter" sound. When the sounds subside, the maggots are dead and the cheese can be eaten.

Health concerns

According to some food scientists, it is possible for the larvae to survive the stomach acid and remain in the intestine, leading to a condition called pseudomyiasis. There have been documented cases of pseudomyiasis with P. casei.

Because of European Union food hygiene-health regulations, the cheese has been outlawed, and offenders face heavy fines. However, some Sardinians organized themselves in order to make casu marzu available on the black market, where it may be sold for double the price of an ordinary block of pecorino cheese.

Attempts have been made to circumvent the Italian and EU ban by having casu marzu declared a traditional food (it has been made in the same manner for more than 25 years, and it is therefore exempt from ordinary food hygiene regulations). The traditional way of making the cheese is explained by an official paper of the local Sardinian government.

A cooperation between sheep farmers and researchers of the University of Sassari developed a hygienic method of production, in 2005, aiming to allow the legal selling of the cheese.

Other regional variations

Outside of Sardinia, similar milk cheeses are also produced in the French island of Corsica, as a local variation of the Sardinian cheese known as casgiu merzu, as well as in a number of Italian regions.

• Bross ch'a marcia in Piedmont;
• Cacie' Punt ("formaggio punto") in Molise;
• Casu puntu in Salento (Apulia);
• Casu du quagghiu in Calabria;
• Gorgonzola coi grilli in Liguria;
• Frmag punt in Apulia;
• Furmai nis ("formaggio nisso") in Emilia-Romagna;
• Marcetto or cace fraceche in Abruzzo;
• Salterello in Friuli-Venezia Giulia.

Several other regional varieties of cheese with fly larvae are produced in the rest of Europe. For example, goat-milk cheese is left to the open air until P. casei eggs are naturally laid in the cheese. Then it is aged in white wine, with grapes and honey, preventing the larvae from emerging, giving the cheese a strong flavour. In addition, other regions in Europe have traditional cheeses that rely on live arthropods for ageing and flavouring, such as the German Milbenkäse and French Mimolette, both of which rely on cheese mites.