Titin-derived peptides as processing time markers in dry-cured ham.

The complex proteolysis in Spanish dry-cured ham processing generates large amounts of small peptides and free amino acids which are responsible for the characteristic texture and flavour of this traditional product. The aim of this work was to study the degradation of the giant protein titin throughout the dry-curing process (2, 3.5, 5, 6.5, and 9 months) through the use of proteomic tools. A total of 320 peptides have been identified by nanoliquid chromatography coupled to tandem mass spectrometry, being some of them identified only at 9 months of processing. In order to confirm the absence of these peptides at other times of processing, MALDI-TOF MS was also employed as a fast and easier technique. Only four peptides, KDEAAKPKGPIKGVAKK, KKLRPGSGGEK, KNTDKWSECAR and ISIDEGKVL, were exclusively identified at 9 months of curing by using both methodologies so that these peptides could be used as potential biomarkers of dry-cured ham processing time.