Influence of crossbreed on the degradation of myofibrillar proteins and on the cathepsin B+L activity in dry cured hams

Enzymatic activity and proteolysis undergone by the proteins extracted from the Semimembranosus and Biceps femoris muscles using high ionic strength buffer were studied in raw hams and hams dry-cured for 11 months. The hams were taken from three different crosses of three breeding enterprises: cross A (75% Duroc-25% Landrace); cross B (50% Duroc-25% Landrace-25% Large White); and cross C (75% Duroc-25% Landrace). Higher cathepsin B+L activity levels were recorded in the Semimembranosus muscle than in the Biceps femoris muscle both in the raw hams and in the cured hams, residual enzymatic activity in the hams being 1% of the initial levels; significant differences were not found for the three crosses. The proteolysis index was higher for the Biceps femoris muscle, similar values being observed for all three crosses. The raw hams from cross A exhibited the highest relative density values for low molecular mass peptides and the lowest relative density values for high molecular mass peptides. After 11 months of curing, proteolysis levels were highest in the hams from cross B, which had the highest levels of 8, 9 and 22 kDa fragments (in the Semimembranosus muscle) and 25 and 9 kDa fragments (in the Biceps femoris muscle). This finding confirms that genetic factors have an influence on proteolysis.