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Quantitative authenticity testing of buffalo mozzarella via αs1-Casein using multiple reaction monitoring mass spectrometry

Gunning, Yvonne, Fong, Louis K.W., Watson, Andrew D., Philo, Mark, Kemsley, E. Kate
Food control 2019 v.101 pp. 189-197
alphaS1-casein, amino acid sequences, amino acids, buffalo milk, buffaloes, mass spectrometry, milk, monitoring, mozzarella cheese, peptides, pizza, restaurant foods, restaurants, supermarkets, surveys, United Kingdom
We address the detection and quantitation of bovine milk in ‘buffalo’ mozzarella cheese using multiple reaction monitoring (MRM) mass spectrometry (MS). Focussing on the abundant protein αs1-casein, present in both species but with 10 amino acid sequence differences, we extract a list of marker peptides specific to each species. ‘Identical’ peptides, exactly the same in both species, are used for relative quantitation of αs1-casein in each milk type, whereas ‘similar’ peptides, present in both species but differing typically by one amino acid, are used to demonstrate relative quantitation in binary cheese mixtures. In addition, we report a pilot survey of UK supermarket and restaurant products labelled as ‘buffalo mozzarella’, finding that 2/3 of restaurant meals and supermarket pizzas are either mislabelled or adulterated.