Sabrina Longley has spent her days both crafting cheese and studying it—and now the Ph.D. researcher has discovered that the bacteria making three Oxfordshire cheeses delicious might also be nourishing the people who eat them.
Working at Nettlebed Creamery, Longley and her colleagues at the University of Reading's Food Microbial Sciences Unit have mapped the microbial and biochemical profiles of three artisan cheese varieties across their entire maturation journey. Their findings, published in ACS Food Science & Technology, reveal that the aging process does far more than create complex flavors—it builds a living ecosystem of probiotic bacteria with potential benefits for human gut health.
The three cheeses examined represent the spectrum of British cheesemaking craft. There's a soft white-rind cheese aged for just over a week, a washed-rind semi-soft cheese that takes several weeks to mature, and a semi-hard cheese aged in hay for around nine months. As researchers sampled these cheeses at different stages, they discovered that all three contained bacteria with recognized probiotic potential—microorganisms that can add to populations of beneficial bacteria already living in our digestive systems.
Streptococcus thermophilus, the same bacterium used to start yogurt cultures, remained dominant in the semi-soft and harder cheeses right through to maturity. Lactococcus lactis was present in all three varieties. But the washed-rind and hay-aged cheeses contained something additional: Propionibacterium freudenreichii, which produces propionic acid—a compound linked to anti-inflammatory properties, reduced cholesterol synthesis, and appetite regulation. For cheese lovers who eat the rind, there's an added bonus: the white mold Penicillium candidum produces chitin, a dietary fiber that acts as a prebiotic, essentially feeding other beneficial gut bacteria and stimulating positive changes in the microbiota.
The hay-aging process proved particularly enriching. The mature hay-aged cheese contained nearly four times as many bacterial species as the same cheese earlier in its development, suggesting that time and environment actively expand the microbial diversity inside the wheel. Meanwhile, lactose—the milk sugar that challenges many digestive systems—was almost entirely absent from all three cheeses by maturity, having been broken down by lactic acid bacteria during fermentation. That's a quiet but significant gift for anyone who struggles with dairy.
What makes this research especially meaningful is how it validates what artisan cheesemakers have long intuited: that the aging process creates complexity through microbial work. As Longley explained, "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, making cheese an excellent vehicle for delivery of probiotics to the gut."
The researchers are careful to note that further dietary intervention trials are needed to confirm how these bacterial populations actually behave in the human gut and what their overall effects might be. But this foundational work transforms cheese from a simple pleasure into something more—evidence that tradition, craft, and science can align to nourish us in ways we're only now beginning to understand.