To protect Swiss cheeses from counterfeiting, Agroscope has developed marker cultures from lactic acid bacteria that allow the origins of the cheese to be determined. Proof-of-origin cultures for extra-hard cheeses are now also available.
In 2008, Agroscope developed a method for protecting Swiss cheese varieties from counterfeiting. This is done with the help of naturally occurring lactic acid bacteria that do not affect the taste of the cheese. These bacteria serve as proof-of-origin markers. Just a few grammes of cheese are sufficient to identify the unique gene sequence of the marker bacteria and thus distinguish the genuine cheese from the imitation. This means that counterfeiting can also be detected in grated cheeses as well as cheese slices or rosettes.
Ten years ago, a proof-of-origin culture (POC) of this type was used for the first time as a marker for the production of PDO (= Protected Designation of Origin) Emmentaler cheese. Now, researchers have also succeeded in identifying naturally occurring lactic acid bacteria which remain detectable for at least 26 months in extra-hard cheese.
Natural Lactic Acid Bacteria as a Proof-of-Origin Marker
Consisting of two marker bacteria, the POC is added to the milk along with the usual cheese cultures during the cheesemaking process. The bacteria remain stable in the cheese for the entire maturation period. Agroscope makes the POC available to the dairies certified to manufacture the relevant PDO variety.
The quest for a POC for extra-hard cheese involved examining over 2000 bacterial strains as to their suitability. In order to make the short list, the bacterial strains had to meet the following criteria:
- No gas-formation potential, since holes in extra-hard cheese are usually unwelcome
- Temperature tolerance vis-à-vis high scalding temperatures in the production of extra-hard cheese
- Unique DNA sequence enabling unequivocal identification
- Highest possible survival rate after freeze-drying
- Safety and harmlessness
- Identifiability during maturation
- No impact on cheese quality.
In recent years, the protection provided by POCs to hard and semi-hard cheeses has more than proven its worth. In addition to further developing the POCs, scientists have been evaluating the efficacy of detection in special cheese products (e.g. processed cheese, fondue mixtures or grated-cheese mixtures) as well as a portable rapid test for analysis outside the laboratory.
- With the help of naturally occurring lactic acid bacteria added during the cheese production process, we can identify counterfeit cheeses. The marker bacteria are extensively tested to ensure that they will not impair the quality of the cheese.
- For extra-hard cheese, these cultures must remain identifiable for at least 26 months. This is what made the search for such cultures so difficult.
- In principle, similar applications in other fermented foods or outside of the food sector are possible.