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We devised and deployed a multimodal characterization approach to profile the proteins in the semimembranosus, the major pig ham muscle carrying the defect. For the first time, this PSE-like destructuration defect was spatially profiled using matrix-assisted laser desorption/ionization–time-of-flight (MALDI-TOF) mass spectrometry imaging on histological sections of destructured and normal semimembranosus samples cut from the inner and outer parts of the muscle. Using this data, we reconstructed tissue-scale ionic maps of PSE-like and normal hams. In another first, the study demonstrated spatial variability of the destructuration defect, largely through the associated peak intensities of four ions expressed as mass-to- harge ratios (written m/z): m/z 4128.7, m/z 4155.6, m/z 5442.5, m/z 8565.0. The first two ions, which are more intense in the inner part of PSE-like ham, have a mass shift of 27 Da that could be due to oxidation of arginine. The spectral signature of the outer zone of PSE-like hams was closer to that of normal hams than to the signature of the inner zone of PSE-like hams, i.e. where the defect localizes most.

These findings open up new perspectives for pork quality classification by defining a set of potential biomarkers of the PSE-like destructuration defect. These pioneering results in food quality science extend the knowledge model on PSE-like destructuration in cooked ham, and prove that mass spectrometry imaging is relevant to cutting-edge food science. We continue to press ahead with the studies on ham, while new studies have started on new food matrices.