Buffalo milk commands a premium price compared to cows’ milk, and is used to make mozzarella cheese. Products labelled as “buffalo mozzarella” must be made solely with buffalo milk, and not with milk from any other species. Reseachers at the Quadram Institute, Norwich have developed a new multiple reaction monitoring (MRM) mass spectrometry (MS) assay measuring the mass of ‘marker’ peptides which, due to the amino acid sequence differences, are characteristic of either buffalo or cow in αs1-casein. The markers can also be used to give relative quantitation for mixtures of bovine and buffalo milk or cheese, based upon ratios of transition peak areas.
The method was used to conduct a pilot survey of retail mozzarella products. Eight samples of supermarket cheeses specifically labelled as buffalo were all found to be 100% buffalo. Five other samples, simply labelled mozzarella, were all 100% cow. These samples showed no signs of adulteration. However, when 17 other products such as pizzas were examined, two thirds of these samples from supermarket pizzas, restaurant pizzas and other restaurant dishes that claimed to be buffalo mozzarella contained at least some cows’ milk. In some cases, the mozzarella was 100% derived from cow.