Mold Causes Black Rot in Northeast Artisan Cheeses

Researchers have identified two Aspergillus molds behind black rot appearing in artisan cheeses at cave-aged facilities in three New England states.

Updated on Nov. 1, 2026 in Organic Food

Mold Causes Black Rot in Northeast Artisan Cheeses

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Researchers identified Aspergillus westerdijkiae and Aspergillus ostianus as the molds causing black rot in artisan cheeses in Massachusetts, Connecticut, and Vermont. Producers stopped the rot by lowering cave temperatures to 50 degrees Fahrenheit or below.

Why it matters

At least one of the identified molds can produce toxins, and the contamination affected cheeses aged in cave environments meant to support helpful rind microbes. The findings matter for U.S. cheesemakers relying on cave aging and for consumers of artisan cheese.

Researchers isolated multiple distinct strains of both molds across facilities and found more than 1,000 genes became more active when A. westerdijkiae was grown on cheese. Whether the molds' toxin-producing potential poses a risk to consumers has not been established.

The players

Benjamin Wolfe

Benjamin Wolfe is a microbiologist at Tufts University who helped identify the molds and said salt may be a fruitful area of future research on how spoilage molds spread.

The details

Black flecks appeared on goat cheese, fuzzy white growth with dark gray marks on other cheeses, and dusty black patches on cheddar. Researchers isolated strains from contaminated rinds and compared their genomes, and Tufts University microbiologist Benjamin Wolfe led the identification.

Over the past decade, Aspergillus spoilage contamination events have occurred at cheese facilities in Massachusetts, Connecticut, and Vermont.

Culture Shift

The discovery connects to a broader pattern in which Aspergillus species in the Circumdati group, known to produce ochratoxins linked to kidney damage, are now appearing in a food category built around controlled natural fermentation. Artisan cheesemakers' reliance on cave environments is being re-examined as part of that shift.

For people who eat artisan cheese, the findings raise questions about whether toxin-producing molds could appear in products they buy, though no outbreak link has been established. Consumers can watch for visible black, fuzzy, or dusty growth on cheese rinds.

The takeaway

Cheesemakers found that lowering cave temperatures to 50 degrees Fahrenheit or below stopped the rot, a practical step for producers managing similar contamination. The discovery shows that controlled natural aging environments still need close monitoring for unexpected molds.