ILLEGAL worm cheese, also known as Casu Marzu, has been around for centuries. Here are 5 interesting facts about this forbidden delicacy.
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5 AMAZING facts about "The World's Most Dangerous Cheese"
5 AMAZING facts about "The World's Most Dangerous Cheese"

What is the price of a casu marzu wheel? Nobody knows for sure. It is ILLEGAL to market it or serve it in restaurants: Casu Marzu is not for sale. Is it safe to eat Casu Marzu? The European Union says no, countless generations of long-lived Sardinians say yes?

Today eDairy Market presents 5 facts about Casu Marzu, the worst cheese in the world:



1. Casu Marzu has been the Robin Hood of cheeses for over 50 years:

Pecorino islands , serves as the base for Casu Marzu. Fiore Sardo cheese, the “flower of Sardinia”, is the island’s pecorino (made from sheep’s milk). This cheese is often the base for Casu Marzu, the “rotten cheese”.

casu marzu
Author: Shardan

This unusual delicacy is the best of the best that the beautiful Italian island has to offer, from a gourmet’s point of view, and yet an Italian law banned Casu Marzu a long time ago: in 1962!

European regulators made things even worse 40 years later. The implementation of a regulation, in 2002, made the production and sale of “rotten cheese” illegal. Not only in Italy, but throughout the EU common market. Ironically, the name Pecorino Sardo had enjoyed a European PDO (Protected Designation of Origin) title since 1996. In 2004, the Sardinians applied to obtain a PDO for Casu Marzu as well, in an attempt to react to the ban.

Las calles de Cerdeña

Unfortunately, the authorities denied the application. Rotten cheese is still banned, although supporters hope this will change. And, that the new rules on Novel Foods will pave the way for some solution soon.

What was the reason for the ban on Casu Marzu? insects Larvae, to be precise. The phiophila casei fly, it’s the meticulous artisan.

Mosca Piophila casei
John Curtis [Public domain], via Wikimedia Commons
The fly transforms a good traditional cheese like Sardinian Pecorino into the extraordinary Casu Marzu. By eating and digesting it. And the larvae STAY in the cheese and are eaten with it. Alive.

EU prudery when it comes to food safety and hygiene standards is well known even on minor issues. Live maggots in food? No way, for the EU rulers. they consider it as an infestation .

In fact, the presence of fly larvae in Casu Marzu is not only desirable and encouraged… it is indispensable. There would be no Casu Marzu without maggots. Just as there would be no bread, wine and cheese without fermenting bacteria.

The production of Casu Marzu never stopped, even though its sale was forbidden.

Several small farmers, especially in the interior, produce it. Officially, only for their own consumption. Today they receive good money from gourmets and well-to-do tourists from all over the world.

Is Casu Marzu expensive?

As for all illegal goods, the scarcity and the dangers of getting hold of them drive up the price of casu marzu. There are no official price lists out there. Because this so-called black market works on the principle “everybody knows somebody…” Which means you can only get Casu Marzu by word of mouth – nobody likes high EU fines! Some claim that Casu Marzu sells for at least $100 per pound, others that it’s only 20 euros per kilogram….

The production was saved from total illegality thanks to a move by Region Sardinia. Which included Casu Marzu in the database of traditional Italian agricultural food products . Which gave way to an exception to the sanitary regulations. As a result, farmers can make cheese with worms… but neither they nor the stores or restaurants can sell it.


2. Rot is not always a bad thing:

Where did the idea of cheese with maggots come from in the first place?

There is no exact record, Sardinians have been making Casu Marzu for longer than anyone can remember. It’s actually something so simple, a natural process, that it surely must have happened: an elderly shepherd discovered that a wheel of cheese that had gone bad and was full of maggots was…. delicious! What started as an incident turned into technology.

That’s how it happens:

Queso de gusano

When it comes to food it’s often associated with bad odors and health risks. When it comes to pecorino, a little magic happens. Enzymes from phiophila casei, the tiny black cheese fly, have the power to break down fats in cheese paste. The flies are attracted to the strong smell of cured pecorino. They lay their eggs in it (farmers facilitate this by piercing the top rind of the cheese wheels and even softening it with a little olive oil). After a while, tiny translucent white larvae hatch and begin to gorge themselves on the cheese.

The rich creamy and tasty Casu Marzu is …. what the worms have shat! That’s right, the cheese goes into the worms, but it also has to come out. That way… You really don’t have to worry: those babies were born in cheese and only ate cheese.

The result of their work is a smooth and creamy product, more liquid than solid.

How does Casu Marzu taste?

Cheese experts often describe the flavor as similar to gorgonzola, but stronger. Spicy, with a touch of bitterness. Long persistence in the mouth. Fermentation alone would not be enough to initiate such an extraordinary transformation. What attracts the flies in the first place is actually the decomposition. The cheese has to start decomposing for the whole process to begin. That said, keep in mind that being processed by the maggots gives new life to the decomposing matter…that’s why the larvae have to be alive when Casu Marzu is consumed.

Now, you may still be wondering…. How do you know if Casu Marzu has really gone bad?

Dead maggots would be a sign that the cheese has really gone bad, and this time beyond repair.


3. Guinness World Records awarded Casu Marzu the title of “most dangerous cheese in the world”:


In 2009, the worm cheese became the “world’s most dangerous cheese to human health,” according to Guinness World Records. “Some of those who have tasted it have felt its ‘burn’ and even suffered irreparable damage to the stomach,” states an article published by Café Babel .

The danger described by Guinness referred to the possibility of the worms in Casu Marzu surviving digestion in the human stomach… and traveling beyond the gut where they could cause damage.

Now, you may be curious…

Can humans really be infested by worms? Absolutely.

An infestation of live humans (or animals) by live fly larvae is called myiasis.

“Intestinal myiasis occurs when fly eggs or larvae previously deposited in food are ingested and survive in the gastrointestinal tract. Some infested patients have been asymptomatic; others have had abdominal pain, vomiting and diarrhea” – definition from the Centers for Disease Control and Prevention , U.S. Government.

Guinness’ statement was obviously a big hit worldwide. Ten years later, the definition is maintained in Casu Marz and still appears everywhere on the Internet. Associating the Sardinian specialty with the definition of “most dangerous cheese in the world”. That and a 1952 report are about all you will find, not much to back up the claim.

What you will NOT find is a serious epidemiological study to confirm or deny this claim. Sardinians, who have been eating worm cheese for generations beyond recall… swear that Guinness’ claims are lies. And proudly boast of the famous longevity of their island’s inhabitants.

Cheese fly larvae have the ability to withstand the acidic environment of the human stomach for up to 120 hours. But since 1952 there have been no known reports of myiasis caused by the consumption of Casu Marzu.

Infestation would mean that the worms stayed in the intestine, did not pass through… and tried to bury themselves in human tissue.

An important little fact: the jumping fly (this other name for the bug is due to the ability of the larvae to JUMP as high as 9 inches, i.e., 15 cm, when disturbed) is about half the size of the common house fly: 4.5 mm. on average for the male and 5 mm. for the female specimen.

Larvas saltadoras

Cheese “worms” are also very small, about 5 mm, with teeth less than a tenth of a millimeter.

If they survive by being eaten by humans who eat cheese in the first place. However, some other Sardinians took the issue of hygienic standards seriously. The University of Sassari had launched a research project as early as 2005. Their dilemma was of a different nature….

Where does all the little cheese fly stop before landing on those cheese wheels?

In other words, a health hazard is more likely to derive from the pathogens picked up by the adult flies than from the larvae themselves. The traditional procedure for making casu marzu leaves it all up to nature. Where the fly has been before, what it has been feeding on… is not a matter for the herders.

However, there is a possibility that they may carry pathogens. Entomologies in Sassari wants to create controlled conditions for rearing cheese flies. Provide farmers with “clean” maggots to inoculate their pecorino. They hope to get rid of bans by ensuring traceability of this unusual “ingredient”.


4. British chefs made Casu Marzu even more famous:

In 2011, a couple of UK celebrities contributed to renewed attention for the striking Sardinian cheese.


Star TV chef Gordon Ramsay and food critic and writer Tom Parker Bowles (son of Camilla Parker Bowles, wife of Prince Charles of Wales). Tom had to see it alone, so he packed his bags and traveled to Sardinia. A local farming family introduced him to the secrets of cheese making. They involved him in the whole procedure, from milking the sheep to making pecorino… and from there Casu Marzu.

This is how Casu Marzu is produced.

1. The first step in making pecorino is to boil sheep’s milk in a large bucket with rennet.

Rennet is a coagulating agent. That is, it separates the curd from the whey. It consists of a set of enzymes produced in the stomach of ruminant mammals. Pecorino rennet is obtained from lamb or cow stomachs. The coagulation action is rapid. A half hour of stirring the milk at an average temperature of 35 C is sufficient to separate the curd from the whey. The curd is then placed in molds, allowed to drain and then cooked.

2. Adding the right amount of salt  

A certain number of hours in a salty solution ( salamoia ) is required as part of the process. When making Casu Marzu, this should be kept to a minimum. Because a pecorino that is too salty would deter flies from laying their eggs in it. Also, the cheese wheels are not turned as often as they normally would be.

3. Then it depends on nature and the weather.

The flies will find their way into the cheese and, with a little help from humans (* holes in the rind), into it. It takes up to three months of ripening for them to do their job.

Cazu Marzu production in season: You have to take into account the life cycles of both the sheep/lambs and the flies. Insects need warm temperatures (at least 25 C, although they can withstand twice that). Which makes this activity a spring and summer business. It goes well with allowing the ewes to milk their lambs.

Cheese making can occur approximately between May and October, under natural conditions. Tom’s adventure in Sardinia includes participating in a traditional family lunch. With crowds of diners of all ages and cramming Casu Marzu in company. Along with many glasses of strong Cannonau red wine.

That’s absolutely realistic, for example, the way the whole thing happens in Sardinia. Change of scenery and off to the set of “The F Word” with Gordon Ramsay. Ramsay makes a show of eating Sardinia’s outlaw delicacy, worms and all, in front of the cameras.

So, two years after the dubious glory received for the Guinness stunt, Casu Marzu was back on stage. Undoubtedly, this contributed to even more foreign tourists and food lovers exploring the Mediterranean macchia in search of the forbidden gourmet treasure.


5. Wageningen University has conducted research on the “Unsafe Casu Marzu”:

ilustración de la ciencia

There is more to the Casu Marzu story than sensationalism.

In February 2018, a recent master’s thesis was discussed at the prestigious Dutch Wageningen University on the question, “Can Casu Marzu be considered safe according to Article 14 of Regulation (EC) No. 178/2002?”

The author, Yvette Hoffmans, presented the case in up to 80 pages.

“In early 2017, an evening course called Insects and Society crossed my path. During this course, I learned about the wonderful world of insects and it showed me how beneficial insects can act as food and feed. Casu Marzu was one of the examples. of insects as food consumed within the European Union,” Yvette explains in the preface.

We are talking about serious official research here , as stated in the paper:

“The thesis is a compulsory part of the Master’s program Food Safety Law at Wageningen University. This thesis is carried out in the chair group Law and Governance. “

Why this thesis is a very useful read not only for Casu Marzu aficionados?

But also for entomophages in general?

Because the author has come to a very burning question point in:

What is considered acceptable/legal by the European Union… when it comes to health safety requirements for putting specific products on the market?

The basic research question of the master thesis is:

Can Casu Marzu be considered safe according to Article 14 of Regulation (EC) No. 178/2002?

Una ilustración de un documento.

Seemingly simple, right? Well, it isn’t.

“Article 14 of Regulation (EC) No. 178/2002 states that food shall not be placed on the market when it is unsafe. The same article further explains that unsafe food may be injurious to health or unfit for human consumption and how these particular definitions are to be applied in relation to foodstuffs.”

In a couple of lines you get a concentration of concepts that are actually quite complicated to interpret.

So much so that the author breaks them down into three distinct chapters.

The three chapters:

  1. A complete analysis of the EU legal framework (including several EU regulations),
  2. A comparative study of other foods that present even more potential risks than Casu Marzu (although they have been on the market forever).
  3. A discussion of what makes a food “fit” or “unfit” for human consumption.  Describing what you can learn if you can stomach dozens of pages full of information.

You see, Casu Marzu could be very important to the future of entomophagy, if put under the spotlight in the right way.

Not as a curiosity, a rare thing that wild Sardinians do (eat) on their distant island.

Casu Marzu is a shining example of the clash between centuries-old tradition and modern concerns about food safety.

And the star of the show is… an insect.

So, after reading all this, you’re probably wondering….

Is Casu Marzu safe? Probably…

But we’re not in a position to give you an answer.

Perhaps, these two excerpts from the study mentioned above will guide you in the right direction.

From the comparison study, you can see that Casu Marzu may present risks, but that other products, widely marketed within the EU, may also present risks. The highest risk in larvae is unlikely to occur in the case of Casu Marzu. In addition, some hazards identified in Gorgonzola, oysters and mushrooms may easily pose a risk to their consumers as it approaches the dose-response or legal limit.

In the last section of the study, Ivette wrote:

I see possibilities in the future for a safe Casu Marzu with the implementation of Regulation (EU) No 2015/2283. Since 2018, insects are considered as novel food. This would make it possible to market larvae throughout the EU. Rearing larvae under monitored conditions in order to use them as raw material in Casu Marzu would be a solution to consider.


Would you like to try this cheese with larvae?



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