Proteolytic pattern of myofibrillar protein and meat tenderness as affected by breed and aging time

The effects of breed and aging time (1, 7, 14, 21 days) were evaluated on meat tenderness and on proteolysis in 24 young bulls from Romagnola × Podolian crossbreed, Podolian and Friesian breed. Shear force decreased with aging in all breeds and showed the highest values at 1 and 7 days in Podolian meat. Myofibrillar fragmentation index significantly increased in Podolian meat throughout aging whereas in Friesian and in Crossbreed meat it increased only in the first week. Proteolysis was investigated by SDS-PAGE and 2-dimensional electrophoresis showing a different quantity and expression profile of myofibrillar proteins among breeds. In all breeds a decrease of troponin-T and an increase of troponin-T derived polypeptides during aging were observed. The highest decrease of troponin-T together with the presence of fragments of MHC in Podolian meat during aging was an outcome of a more extensive proteolysis in this breed. Data suggest that tenderness and proteolytic changes during aging are related to animal's breed.