The cheesy flavor of microbes

Cheddar’s microbial mastery

Making a cheese with a particular flavor turns out to be biochemically complex. Cheese makers already know that flavors and texture are strongly influenced by factors such as types of milk and rennet, as well as the duration and location of ripening. But a recent study by a panoply of scientists in Europe found that cheeses made with the same ingredients can differ wildly in flavor according to the presence and combination of certain microbes (Nat. Commun. 2023, DOI: 10.1038/s41467-023-41059-2).

Led by Chrats Melkonian, a cheese lover and bioinformatic scientist specializing in microbial ecology and evolution at Utrecht University, the team of scientists embarked on a yearlong investigation of the factors influencing the taste of cheese using cheddar—a hard, yellow cheese created in Cheddar, England.

The researchers nibbled their way toward the discovery that two key microorganisms—Streptococcus thermophilus and certain strains of Lactococcus—are central to cheddar’s nutty and creamy flavors. They also found that Lactococcus microbes rely on the presence of S. thermophilus microbes to provide nitrogen, which the lactococci depend on for their survival.

The complexity doesn’t end there: the scientists discovered that the presence of Lactococcus cremoris limits the formation of four-carbon compounds such as diacetyl and acetoin, which in small amounts result in a buttery aroma but in larger concentrations result in a cheese with an off-flavor.

Melkonian still loves cheese even after the intensive research project. “Can one even get bored of cheese?” he asks Newscripts.

The study means cheese makers are a step closer to being able to select a menu of flavors according to the proportion of certain microbes they add to the mix. The first makers of cheddar, who are thought to have begun their craft in the 12th century, inadvertently selected their microbial mix by placing their cheese in the bacteria-rich caves of Cheddar Gorge.

World’s smelliest cheese?

Cheese enthusiasts should proceed with caution—and possibly hold their noses—if they ever experience a Minger. It is a brie-style cheese, which its producer, the Scottish artisan cheese maker Highland Fine Cheeses, claims to be the smelliest in the world.

“It’s got that slightly sulfurous, odious cabbagey smell,” Rory Stone, its creator and head of the firm, tells Newscripts. Appropriately, minger in UK slang means “ugly.”

The smell seems to get stronger the longer you have it around. “You put it in the fridge, and when you come back half an hour later, it really has done its stuff. It just takes that time, and you’re aware that somebody needs to get the dog out of the house,” Stone says. “There’s just a really pretty off-putting whiff that’s following you around the house.”

On the other hand, the flavor is “surprisingly mild,” Stone says. “I would liken it to a pretty ripe Camembert. A good Minger with a nice, hot sourdough toast and butter smeared across the top—it’s something you just can’t quite eat too much of,” he says.

Stone created the Minger almost by accident. There was extraneous mold on the rind of some blue cheeses Stone was making, so he decided to wash them in brine to see if this would inhibit the mold.

When he unwrapped the cheeses from their protective foil some 6 weeks later, their rinds had turned orange. The salt wash had pushed the pH above 5.4, promoting the growth of Brevibacterium casei.

This bacterium, which is also the source of body odor in people, is why the Minger stinks. “Brevibacterium likes to live in hot, sweaty places in your body, in your armpits, on your feet, around your crotch,” Stone says.

Beyond the human nose, there is no recognized system to verify Stone’s claim that he has made the world’s strongest-smelling cheese, but on this occasion the Newscripts team chose not to request a sample.

Please send comments and suggestions to newscripts@acs.org.