Cheese can seem like a simple pleasure, but every bite is the result of a microscopic transformation. As milk becomes cheese, bacteria and fungi break down sugars, proteins, and fats, creating the flavors, aromas, and textures that make each variety distinct. New research suggests that some of these tiny cheesemakers may do more than shape flavor. They could also help explain why certain traditional cheeses may interact with the gut in interesting ways.
Scientists at the University of Reading studied three artisan cheeses made by a small British artisan creamery in Oxfordshire to see how their microbial life changed as they matured. The team tracked both the bacterial communities and the chemical makeup of the cheeses during aging, revealing how fermentation helps build a cheese's character from the inside out.
The study examined a soft white-rind cheese aged for just over a week, a washed-rind semi-soft cheese matured over several weeks, and a semi-hard cheese aged in hay for about nine months.
Lead author Sabrina Longley, a PhD researcher in the Department of Food and Nutritional Sciences, said: "Good cheese is delicious, and the artisan varieties we studied are full of microbial life.
"The aging process creates more complex aromas and textures through the work of an army of helpful bacteria. The matrix of fats and proteins in the cheese may also help protect the bacteria as they travel along the digestive tract, which could make cheese a useful vehicle for carrying probiotics to the gut."
Beneficial Bacteria in Every Cheese
Researchers collected samples at several points during cheese maturation and analyzed their bacterial communities and chemical makeup.
Each cheese contained bacteria with recognized probiotic potential. Streptococcus thermophilus, also used as a yogurt starter, remained dominant in the semi-soft and harder cheeses through maturity. Lactococcus lactis was found in all three cheeses throughout the process.
The washed-rind and hay-aged cheeses also contained Propionibacterium freudenreichii, a bacterium that produces propionic acid, one of the fermentation compounds researchers are still working to understand.
People who eat cheese rind may have another reason to enjoy it. The white mold Penicillium candidum, used to create the rind of the soft cheese in the study, produces chitin, a dietary fiber that may act as a prebiotic. Prebiotics feed beneficial gut bacteria and may help encourage changes in the gut microbiota.
Hay Aging and Microbial Diversity
Aging the harder cheese in hay appeared to increase its microbial diversity as it matured. By the end of the process, the mature cheese contained nearly four times as many bacterial species as it had earlier in maturation.
The researchers also found that lactose, the sugar in cow's milk that some people have difficulty digesting, was almost entirely gone from all three cheeses by the time they reached maturity. Lactic acid bacteria had broken it down during fermentation.
The authors say more research is needed to determine how these bacteria behave in the gut after the cheese is eaten, how they affect the gut microbiota, and what their broader effects may be.