Detection of undeclared bovine milk in different food matrices by a multi-technique approach

The official method (i.e., isoelectric focusing, IEF) for the detection of bovine milk in cheeses obtained from ovine, caprine or buffalo milk, according to the Commission Implementing Regulation (EU) No 150/ 2018, was compared with three techniques: lateral flow immunoassay (LFA), ELISA and real-time PCR (RT-PCR). Samples of milk, cheese and vegetable drinks were analysed as control samples and after artificial contamination with bovine milk at different concentrations. All these assays, except for ELISA, showed a good diagnostic performance able to detect milk adulteration at concentrations lower than 1% of bovine milk in caprine, ovine and buffalo milk. Relative sensitivity, specificity and accuracy of both ELISA and RT-PCR compared with IEF were 100%, whereas for LFA they corresponded to 100%, 62.5% and 72.7%, respectively. A good agreement among ELISA and RT-PCR versus IEF was observed but only a moderate agreement between LFA and IEF