{Reference Type}: Journal Article {Title}: How processing affects marker peptide quantification - A comprehensive estimation on bovine material relevant for food and feed control. {Author}: Stobernack T;Höper T;Herfurth UM; {Journal}: Food Chem {Volume}: 454 {Issue}: 0 {Year}: 2024 Oct 1 {Factor}: 9.231 {DOI}: 10.1016/j.foodchem.2024.139768 {Abstract}: Processing food and feed challenges official control e.g. by modifying proteins, which leads to significant underestimation in targeted, MS-based protein quantification. Whereas numerous studies identified processing-induced changes on proteins in various combinations of matrices and processing conditions, studying their impact semi-quantitatively on specific protein sequences might unveil approaches to improve protein quantification accuracy. Thus, 335 post-translational modifications (e.g. oxidation, deamidation, carboxymethylation, Amadori, acrolein adduction) were identified by bottom-up proteomic analysis of 37 bovine materials relevant in food and feed (meat, bone, blood, milk) with varying processing degrees (raw, spray-dried, pressure-sterilized). To mimic protein recovery in a targeted analysis, peak areas of marker and reference peptides were compared to those of their modified versions, which revealed peptide-specific recoveries and variances across all samples. Detailed analysis suggests that incorporating two modified versions additionally to the unmodified marker may significantly improve quantification accuracy in targeted MS-based food and feed control in processed matrices.