La Motte-en-Bauges (France) (AFP)
How to keep and promote good bacteria while avoiding the development of bad ones? This is the secret of French cheeses made from raw milk and a challenge taken up daily by farmers, like at the Savoyard farm "la marmotte en Bauge".
It is 7:00 a.m. In groups of five, the Tarentaise, cows with red coats and eyes bordered with black, hurry towards the milking parlor. Jocelyne Pavy, a hat on his head this chilly morning at La Motte-en-Bauges, at an altitude of 1,000 meters, plugs in his milking machine.
After milking, it goes over each teat with a cloth coated with a mild cleaner, so as not to damage the delicate microbiota, the microorganisms accumulated on the udder of the cow and which will contribute to the flavor of the cheese.
A 2016 study by the French National Institute for Agronomic and Environment Research (Inrae), conducted by researcher Marie Fretin, showed the importance of not completely sanitizing the udder of cows, which alone contains 85 % of the animal's microbiota.
Because with the increasingly drastic health measures taken since the 1970s to avoid the development of dangerous bacteria (listeria, salmonella, E. coli ...), scientists have noted an impoverishment of the richness of the microbiota of farms and their products.
- No pasteurization -
The milking finished, Jocelyne opens the tank tap. The milk (15 liters per cow on average) goes down into a large cauldron located in the farm's "lab", on the floor below. In this room, where all the stainless steel and copper equipment can be washed with large amounts of water, begins the production of Tome des Bauges, a cheese in Protected Designation of Origin (PDO) made from raw milk.
The morning milk is mixed with that of the evening milking to "keep the natural lactic ferments", explains Patrick Pavy, Jocelyne's husband. In a white coat, he slowly warms the milk after adding rennet extracted from the gastric juices of the calf, to acidify it.
"Around 10 degrees, the bacteria start to work," he explains. Here, no pasteurization: Patrick Pavy ensures that the cauldron never exceeds 40 degrees, the temperature at which the precious bacteria that make the tome's taste begin to disappear.
Quite quickly, the texture thickens. The "curd" is formed. With years of experience, Patrick Pavy sees with the naked eye when the transformation is complete: it's time to empty the huge cauldron and mold the curd in dishes that it drains.
A few hours later, the future cheeses are placed on local wooden boards in the maturing cellar. When cool and in the dark, they lose their water and develop bacteria and fungi which will form the crust and flavor.
Every day, the cheese maker turns over the tomes, removes surface mold. A month and a half later, they will be refined and ready to eat, with a nice brown crust.
- Know how -
As in this Savoyard farm, it is the local know-how, the breeding and processing practices which guarantee, in different terroirs of France, very different tastes, textures and flavors to cheeses having all the same base : milk.
This diversity is also linked to the microbial richness of the environment of the farm, contained in particular in the grass which the cows consume.
As part of the MetaDPOcheese research project, in which INRAE is participating, "we found more than 1,400 bacterial species" in raw milk samples from all over France, according to Françoise Irlinger, research engineer in microbiology at the Institute . "This represents 180 to 450 bacterial species" on average for each milk - their number varies depending on the PDO.
In terms of health, these discoveries are also of interest, because nature abhors a vacuum: "The first bacteria to arrive will prevent others from colonizing" and if the good bacteria grow well, that leaves no room for the bad to survive , assures Françoise Irlinger.
© 2020 AFP