Science

VIDEO. Camille’s chronicle: Did Pasteur kill cheese, the real one?

CJAMY. Camille Gaubert’s column is broadcast daily in the program “C Jamy”, presented by Jamy Gourmaud from Monday to Friday at 5 pm on France 5.

When Louis Pasteur invented pasteurization to improve wine production, he probably did not foresee that it would also be widely used for cheese. But while pasteurization has partly killed the diversity of microorganisms that make cheese, it can be an important asset in terms of food security.

80% of cheese pasteurized in France

So much so that in 2018, 90% of cheeses on the French market were pasteurized, the rest being what we call raw milk cheeses. “This is quite low compared to other countries such as Italy or Switzerland where the proportion of raw milk cheeses can reach almost 70 or 80%.“, notes Christophe Chassard, director of the UMRF, INRAE ​​joint cheese research unit. To pasteurize a cheese, the most common technique is to heat it for 15 seconds at 72 ° C, in order to eliminate the The vast majority of bacteria must then be stored in the refrigerator at 4 ° C, a temperature low enough to very significantly slow down the growth of survivors likely to colonize the cheese.

Pasteurize to protect the most fragile

Eliminating bacteria helps protect certain fragile people, such as young children, pregnant women or immunocompromised people. The most dangerous bacteria are Listeria monocytogenes and the Salmonella, responsible for two diseases called listeriosis and salmonellosis. They can in particular cause fevers, diarrhea and vomiting … Even miscarriages or death. “The risks associated with non-pasteurization depend on the type of cheese,” explains Christophe Chassard. “There is not the same risk of pathogenic germs between a cheese which contains a lot of water, such as Camembert, versus a pressed or cooked cheese. The more water there is, the greater the risk that pathogens will grow quickly.

Even raw milk cheese sometimes needs to be handled

But not all of these bacteria are trying to kill us. Some have a beneficial function: they give raw milk cheeses a variety of flavors and aromas. But suddenly, did Louis Pasteur kill the cheese, the real one? It is somewhat true, answers Christophe Chassard. Because if pasteurization allows better control of the product, it tends to smooth the taste, pasteurization has therefore destroyed part of the diversity of bacteria that make cheese. But it’s not that simple: raw milk cheeses can have more than 40 microbial species, but even they can be artificially manipulated. Thus, in Roquefort or Gorgonzola, you must add the mushroom Penicillium roqueforti, to give it its blue lines. Even in raw milk cheeses, it is therefore often necessary to intervene to control the taste or the rind.

Pasteurization is ultimately just a matter of food security. Grated or melted, raw or pasteurized, it’s up to you to choose what suits you. No hard feelings, Louis!

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