Protein modifications in cooked pork products investigated by a proteomic approach.

To evaluate process-induced protein modifications in cooked ham and emulsion sausages, proteomes of whole-cut (Parma and "Praga" cooked hams) and comminuted pork (mortadella and würstel) products were compared to raw pork using two-dimensional gel electrophoresis (2-DE) coupled to image analysis and mass spectrometry (MS). Other than heat-induced breakdown of part of the myosin heavy chains, the 2-DE pattern of cooked ham was substantially similar to that of raw pork. However, the MS-based analysis showed minor modifications, including the extensive oxidation of methionines. In contrast, likely due to emulsification, comminuted sausages were characterized by an abundant insoluble protein fraction(IPF). Interestingly, tropomyosin and myosin light chains in comminuted sausages were exclusively found in the IPF. Our results indicate that the protein aggregation systems of cooked hams and emulsion sausages reflect the processing conditions and are definitely different, the former being characterized mainly by disulphide bridges and the latter by additional covalent inter-protein links. Our results indicate that the protein aggregation systems of cooked hams and emulsion sausages reflect the processing conditions and are definitely different, the former being characterized mainly by disulphide bridges and the latter by additional covalent inter-protein links. Thus, specific signature protein patterns have the potential to be monitored for the a posteriori evaluation of the quality of meat products as well as for authentication purposes.