Feasibility of a capillary LC/ESI-Q-TOF MS method for the detection of milk allergens in an incurred model food matrix

The capability of a capillary LC-Q-TOF mass spectrometer system as a qualitative tool for the identification and confirmation of milk allergens in thermally processed food was investigated. Milk powder incurred cookies were produced in-house and chosen as the model food matrix. To unequivocally assess the presence of milk allergens, samples testing positive to ELISA were analysed by a capillary LC-Q-TOF MS/MS method in order to identify specific peptides that can be used as markers for milk allergens. Results show that α-S1 casein was the protein identified with the highest score (in 100 μg g−1 milk powder incurred cookies) and its identity was confirmed by detection of the peptides m/z 692.86 and 634.34 and their specific MS/MS ions providing a fingerprint for α-S1 casein. Besides that, other milk proteins were highlighted by performing database searching. The proteomic MS-based method employing a capillary LC-Q-TOF system proved to be a valuable tool to carry out qualitative and confirmative analysis to trace contamination of milk allergens in processed food matrices.