The effect of ageing on changes in myofibrillar protein in selected muscles in relation to the tenderness of meat obtained from cross-breed heifers

The aim of this study was to evaluate the impact of the ageing on changes in selected myofibrillar proteins and Warner-Bratzler shear force values in muscles from cross-breed CharolaisexHolstein Friesian heifers. Triceps brachii (TB), infraspinatus (IS), vastus lateralis (VL), semimembranosus (SM), biceps femoris (BF) and semitendinous (ST) muscles after ageing were examined. A significant muscle effect was found in the case of basic chemical composition, Warner-Bratzler shear force values and cooking loss. The vastus lateralis characterised by the lowest intramuscular fat percentage (P0.05). The highest connective tissue content was shown for infraspinatus. This muscle had the lowest Warner-Bratzler shear force values in every ageing time, regardless of the cooking method. Throughout the ageing process, selected myofibrillar proteins were altered in all examined muscles, but at varying rates. The SDS-PAGE electrophoresis and Western blotting analysis showed that desmin and troponin-T degradation affected both muscles and ageing effects (P0.001).