Black spots on cheese solved in Switzerland 

The Swiss cheese industry has been concerned about black spots, which appeared in some cheeses, as it was bad for sales. After an intensive search for the riddle, the national agricultural research institute Agroscope presented the solution: teat sealers, which are used to dry off dairy cows, were the cause. 

These teat sealers contain bismuth as the main ingredient. Although bismuth is a heavy metal, unlike lead or mercury, for example, it is considered harmless and is found in many medicines and cosmetics such as lipsticks. 

When bismuth residues get into the milk and thus into the cheese, they can ultimately cause harmless, but unsightly black spots, especially in cheese that has matured for a long time. 

Agroscope confirms that the Swiss cheese organisations have effectively delt with the problem. Gruyère Switzerland AOP and Etivaz AOP, for example, banned their milk producers from using the bismuth teat sealers. 

“We have not found any new cases and we are not aware of any serious cases with other varieties such as Emmental or Appenzeller,” John Haldemann of the research institute, says. 

“We had damage to more than 100 cheeses. More black spots like this in the cheese could affect purchases and would ultimately lead to even greater damage,” says Philippe Bardet, director of the Interprofession du Gruyère.  

He would like to see more research in this area so that such problems would no longer arise in the future and milk producers would have more options. “We now need solutions from Swiss research,” says Reto Burkhardt of the Swiss milk producer SMP. “Because antibiotics are not an alternative. For the SMP, food safety and harmlessness for consumers and in veterinary medicine have absolute priority. No customer accepts Swiss cheese with black spots.”