Eating cheese, for many, is one of life’s great pleasures. And while cheese-makers and scientists have long understood that bacteria transforms milk into the creamy, flavor-packed product, they haven’t fully understood the roles different microorganisms play in developing the unique flavors of cheeses.
Now, researchers are one step closer to unraveling some of this delicious mystery for cheddar. Their findings, published last week in the journal Nature Communications, could someday help cheese-makers tailor their recipes to produce specific tastes.
“We now have targets of which interactions could affect different bacteria,” says study lead author Chrats Melkonian, a microbial ecologist at Utrecht University in the Netherlands, to New Scientist’s Chen Ly.
Cheese is a fermented food—just like beer, kombucha, kimchi and yogurt, to name a few. To produce it, cheese-makers add bacteria to milk. The bacteria chow down on the sugars present in the milk, transforming them into lactic acid—which helps give cheese (and other foods, like sourdough bread) its tangy taste.
The types of microorganisms cheese-makers add—as well as their methods and the type of milk they use—ultimately determines what kind of cheese they will produce. For example, blue cheese is famously made by adding the fungus Penicillium roqueforti to cow’s, sheep’s or goat’s milk.
To better understand what’s happening at the microbial level, researchers set up a cheddar-making experiment. They made multiple samples of cheddar using different starter cultures that contained varying combinations of bacteria, including Streptococcus thermophilus, Lactococcus cremoris and Lactococcus lactis. They made some of the starter cultures themselves and obtained others from industrial producers.
Once they had their cheese samples in hand, they left them alone to ripen. A year later, they revisited the samples and recorded their microbial populations.
Based on this analysis, they gleaned that S. thermophilus is important for the growth of the Lactococcus strains and helps shape the taste of cheese. The cheddar samples made without S. thermophilus had much lower levels of Lactococcus bacteria at the end of the year of ripening than the other samples did.
They also found that L. cremoris, in particular, is responsible for giving cheddar its distinct flavor, because it limits the development of the chemicals diacetyl and acetoin. Too much of these components can give the cheddar unpleasant “off-flavors,” the authors write, but in moderation, they create a buttery taste. In addition, L. cremoris contributed to the development of compounds that add fruity and meaty flavors to cheddar.
Scientists did not detect any microbial or flavor differences between the cheese produced with hand-made starter cultures and those made with commercial starters, per New Scientist.
Together, the findings help explain the scientific underpinnings of the art of cheese-making. They also confirm the importance of selecting and combining different microbes to achieve specific flavors.
Though past research has explored the roles of individual microorganisms, the paper “brings together the bacterial communication that are at play in the complex metabolic landscape that leads to the overall cheese flavor profiles,” says Bart Weimer, a microbiologist at University of California, Davis, who was not involved in the research, to Chemistry World’s Julia Robinson.