Pork liver tissue-specific peptide markers for food authenticity testing and adulteration detections

A liquid chromatography-mass spectrometry bottom-up proteomic approach was applied for the detection and identification of proteins from liver tissues. We identified 74 unique pork liver peptide markers that are resistant to the thermal processing of food. These peptides are derived from 43 proteins, which perform various functions in the liver. Roasted and sterilised pâté-type products with a pork liver content ranging from 6% to 51% were examined to select the most reliable pork liver peptide markers that survive unmodified in complex processed food matrices. Of the 74 specific heat-stable peptides detected in pure liver tissue, five (GDAPEEEVSLSK, ALTAELEAVGK, TFYLNVLNEEER, AQFGQPEILLGTIPGTGGTQR and VIAPGFNALEQILQSTAGK) were the best candidates to confirm the presence of liver tissue in highly processed meat products. We have identified unique tissue-specific markers that enable rapid and specific identification of pork liver in processed food and may contribute to the development of new methods for testing food authenticity.