What Microbes are In Your Cheese?
Brie, Gouda, Havarti, Manchego, Roquefort. We all have our favorite types of cheese, but what is it actually that makes them all different?
Let’s start with the basics: what exactly is in cheese? Most of us know that it’s made from milk, and if you’re a cheese fanatic you might know a little something about cultures and rennet. At its core, cheese is a fermented milk product, and over the centuries we have learned to master the cheese making process, able to produce a variety of different cheeses around the world.
All cheeses begin with milk — whether it’s cow milk, goat milk, sheep milk, even buffalo milk — and once the initial cheese making stage has been completed to separate out curds and whey, the last, and often most important, one kicks in: aging. While ripening, enzymes and bacteria continue to modify proteins, fats and sugars in the cheese, which ultimately help to develop its distinct look, feel and flavor.
That means that cheese is full of bacteria, particularly the rind. In fact, a single gram of cheese rind contains 10 billion microbial cells, a mix of bacteria and fungi. But what are these microbes?
Researchers Benjamin Wolfe and Rachel Dutton at Harvard University set out to answer this question, bringing in 137 cheeses from 10 different countries to analyze the microbes in the different cheese rinds, the results of which were recently published in Cell. Out of so many different cheeses, they found that there were 10 types of fungi and 14 types of bacteria that tend to dominate. In other words, a very small amount of the same microbes for a variety of cheeses.
On top of that, while countries with cheese making backgrounds are very proud of their heritage, it turns out that geography doesn’t matter all that much. The researchers found no support for the concept of “microbial terroir,” the idea that different places have specific microbial populations that would in turn give a particular cheese its specific flavor, taste, texture, etc. So a similar type of cheese made in France and Spain, while different in origin, would have a similar microbial makeup.
Another interesting finding? The microbes Pseudoalteromonas and Vibrio, bacteria that are normally found in marine environments, even if the cheeses weren’t made anywhere near the sea.
According to Wired, “Wolfe speculates that these bacteria were transferred to cheeses by sea salt used during the cheese making process. ‘All cheeses are salted in various ways,’ he said. In the ocean, these bacteria live on the chitin-rich shells of crabs and other marine invertebrates, he says. In cheese, fungi provide an alternative source of chitin: It’s in walls of their cells. ‘We think cheese makers might be creating the same kind of environment that these bacteria love in the cold damp ocean.’”
The differences in the microbial makeup were mostly related to the types of rind that the cheeses had. Bloomy rind cheeses — soft creamy cheeses that use mold to get them going — tended to have a very different set of microbes than natural rind cheeses, cheeses that have a hard rind like like a comté or a cheddar. Washed rind cheeses — cheeses which tend to be orange and very funky, like a muenster — were somewhere between the two.
Next time you take a bit of your favorite cheese, be sure to thank the microbes.
Photo Credit: Graeme Maclean