Cheese And Flies: An Unlikely Culinary Partnership

Casu martzu, also known as casu marzu, is a traditional Sardinian sheep milk cheese that contains live insect larvae, or maggots. The cheese is deliberately infested with the larvae of the cheese fly, which promote an advanced level of fermentation and break down the cheese's fats. The texture of the cheese becomes very soft, with some liquid (called làgrima, or teardrop in Sardinian) seeping out. While casu martzu is considered a delicacy by some, it is also considered unsafe to eat when the maggots in the cheese have died.

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Casu martzu, a traditional Sardinian sheep milk cheese, is considered unsafe to eat when the maggots in the cheese have died

Casu martzu, also known as casu marzu, is a traditional Sardinian sheep milk cheese that contains live insect larvae or maggots. The cheese is made by boiling sheep's milk at 35°C and adding rennet to it, causing the liquid to coagulate and curdle. After being moulded and soaked in brine, the cheese is left in the open air, where flies lay their eggs inside. These larvae are from the cheese fly of the Piophilidae family and are deliberately introduced to the cheese to promote an advanced level of fermentation and the breakdown of fats. The cheese becomes very soft, with some liquid (called làgrima, or "teardrop" in Sardinian) seeping out. The larvae themselves are about 8 mm long and appear as translucent white worms.

The traditional way of consuming casu martzu is to cut into the cheese and spread it on Sardinian flatbread (pane carasau), often served with a strong red wine like cannonau. The larvae in the cheese are typically eaten as well, although some consumers prefer to kill the maggots first. One method to do so is to place the cheese in a sealed paper bag. As the maggots writhe and jump in the bag due to oxygen starvation, their death is indicated by the subsiding of the "pitter-patter" sound they make. The cheese can then be consumed without the live larvae.

Casu martzu is considered a delicacy in Sardinia and Italy, but it has also gained attention worldwide for its unusual inclusion of maggots. However, it is regarded as unsafe to eat when the maggots have died. This belief has led to the practice of only consuming cheese with live maggots or refrigerating the cheese, which also kills the maggots. While no deaths have been linked to the cheese, experts have warned of potential health risks associated with consuming casu martzu with live larvae. These risks include the possibility of the larvae surviving in the intestine and causing enteric pseudomyiasis, as well as the formation of painful and dangerous lesions.

The production and consumption of casu martzu have faced legal challenges. It was banned in the European Union for some time, and it is still illegal in the United States. However, it has since been granted ''traditional food' status, and producers are working to comply with 'novel food' regulations. Similar cheeses with fly larvae are also produced in other regions of Europe, such as the French Mimolette and German Milbenkäse, which rely on cheese mites.

Casu martzu is produced by deliberately introducing the larvae of the cheese fly to the cheese, promoting an advanced level of fermentation

Casu martzu, also known as casu marzu, is a traditional Sardinian sheep milk cheese that contains live insect larvae, or maggots. The process of making this cheese involves deliberately introducing the larvae of the cheese fly to promote an advanced level of fermentation. This technique takes the cheese beyond typical fermentation to a stage of decomposition, as the larvae break down the cheese's fats. The cheese fly, from the Piophilidae family, lays eggs in the cheese, and these eggs hatch into larvae that are about 8-10 mm long. The resulting cheese has a very soft texture, with some liquid (called "làgrima" in Sardinian, meaning "teardrop") seeping out.

To make casu martzu, sheep's milk is boiled at 35°C, and rennet is added to coagulate the liquid. After obtaining curdled milk, the mixture is put into molds and then into brine after 24 hours. The cheese is then left in the open air, providing an opportunity for flies to lay their eggs. The affinage, or ageing process, lasts a minimum of 15 days to obtain a creamy consistency, as preferred by aficionados in Sardinia and Corsica.

The introduction of cheese fly larvae serves a specific purpose in the production of casu martzu. These larvae contribute to an advanced level of fermentation, enhancing the breakdown of the cheese's fats. This process results in a very soft texture and a pungent, tangy flavour. The cheese is often consumed directly from the wheel, spread on bread, or served with Sardinian flatbread and strong red wine.

Casu martzu has gained a reputation as "maggot cheese" or "grub cheese" due to the presence of live insect larvae. It is considered a delicacy in Sardinia and other parts of Italy, but it is banned in the United States. The consumption of this cheese is considered unsafe when the maggots have died, so it is typically eaten when the maggots are still alive or refrigerated to preserve their freshness. Some consumers choose to avoid ingesting the maggots by placing the cheese in a sealed paper bag, waiting for the maggots to die, and then eating the cheese.

While casu martzu is unique in its deliberate use of cheese fly larvae, other cheeses incorporating live arthropods for ageing and flavouring exist, such as the German Milbenkäse and French Mimolette, which utilise cheese mites. Additionally, the English Stilton cheese was historically served with mites or maggots, though this practice is no longer common.

Other European cheeses that rely on live arthropods for ageing and flavouring include German Milbenkäse and French Mimolette, which use cheese mites

Casu martzu, a Sardinian sheep milk cheese, is well-known for containing live insect larvae (maggots). However, other European cheeses also rely on live arthropods for ageing and flavouring. German Milbenkäse and French Mimolette are two such examples that use cheese mites.

German Milbenkäse, also known as Spinnenkäse or "spider cheese", is a speciality cheese made by flavouring balls of quark (a type of soft cheese) with caraway, salt, and sometimes elderflower. The cheese is then dried and placed in a wooden box containing rye flour and cheese mites for approximately three months. The digestive juices of the mites cause the cheese to ripen and develop a bitter note and a zesty aftertaste. The mites clinging to the rind are typically consumed along with the cheese.

French Mimolette, also known as "Boule de Lille", is another cheese that uses mites in its production. This semi-hard cheese has a spherical shape and a natural rind. The mites used in Mimolette are Acarus siro mites, also known as flour mites. They are intentionally placed on the surface of the cheese, contributing to its flavour and giving it a distinctive greyish colour and crusty appearance. The mites burrow through the cheese, promoting airflow and flavour development during ageing.

Mimolette can be consumed at different stages of ageing, with its flavour profile changing dramatically over time. Younger Mimolette (6 months or under) tastes like mild cheddar, while older Mimolette (over 18 months) is harder to chew and has a hazelnut-like flavour preferred by many. The presence of mites in Mimolette has certainly sparked mixed reactions among consumers, with some finding it intriguing and others feeling hesitant to try it.

Both Milbenkäse and Mimolette showcase unique cheese-making traditions in Germany and France, respectively, where the use of cheese mites plays a crucial role in the ageing and flavouring process.

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English Stilton was once 'wormy' and people loved it

English Stilton, now a protected designation of origin (PDO) cheese, was once wormy and people loved it. Stilton is an English cheese produced in two varieties: blue, which has Penicillium roqueforti added to generate a characteristic smell and taste, and white, which does not. The blue variety is made in a similar way to other blue cheeses, which gain their blue veins and distinct flavour from the use of one or more saprotrophic fungi.

In his 1724 work, "A Tour thro' the Whole Island of Great Britain", Daniel Defoe wrote about English Stilton:

> We pass'd Stilton, a town famous for cheese, which is call'd our English Parmesan, and is brought to table with the mites or maggots round it, so thick, that they bring a spoon with them for you to eat the mites with, as you do the cheese.

The presence of mites or maggots in Stilton cheese was also noted by English author G. K. Chesterton, who wrote several essays on cheese, specifically on the absence of cheese in art. In one of these essays, Chesterton recalls a visit to the small town of Stilton in the fenlands of England, and expresses his deep impression of the cheese in a poem titled "Sonnet to a Stilton Cheese".

While the traditional Stilton cheese may have been wormy at one time, modern Stilton cheese is now produced without the presence of mites or maggots. The production of wormy cheese is now associated with other varieties of cheese such as Casu Martzu, a traditional Sardinian sheep milk cheese that contains live insect larvae or maggots. Similar cheeses with fly larvae are also produced in other regions of Europe, such as Germany's Milbenkäse and France's Mimolette, which rely on cheese mites for ageing and flavouring.

Female cheese flies lay eggs on meats and cheeses, which, when hatched, produce burrowing larvae that are difficult to detect

The process of using fly larvae to break down cheese is not unique to Sardinia. Similar milk cheeses are produced in the French island of Corsica, as well as in some Southern villages in France, where it is known as casgiu merzu or casgiu sartinesu. In Germany, the cheese Milbenkäse relies on cheese mites for ageing and flavouring, and in Egypt, a similar cheese called "mish" is produced.

The practice of deliberately infesting cheese with fly larvae is not without its risks. Casu martzu has been described as "dangerous maggot cheese" or "grub cheese", and the larvae can cause painful and dangerous lesions in the intestines if they settle there. However, no cases of illness have been linked to the cheese. The cheese is considered unsafe to eat by Sardinian aficionados if the maggots are dead, so only cheese with live maggots is usually eaten. Some consumers choose to place the cheese in a sealed paper bag before eating it. The maggots, starved for oxygen, writhe and jump in the bag, creating a "pitter-patter" sound. Once the sounds stop, indicating that the maggots are dead, the cheese is considered safe to eat.

While some may be deterred by the idea of eating cheese with maggots, others embrace it as a delicacy. In Italy, maggot-infested cheese is considered a delicacy, and some consumers of homemade cheese have expressed a willingness to eat their cheese even after discovering maggots, as long as there are no signs of spoilage.

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