Variation in the maximum shear force, MSF, for raw meat during storage at 0, 4 and 10 °C was as shown in Fig. 1. There was no significant difference (P > 0.05) between aerobic and vacuum conditions for the MSF value at different storage temperature. Texture parameter reflected a progressive softening in the raw meat during storage at 4 °C and 10 °C, for both films. On the other hand, at 0 °C the MSF showed no variation for period of time studied.
Changes in meat tenderness of raw beef during storage have been reported in several studies. According to Koohmaraie (1996) and Zhang et al. (2005), after 24 h post-mortem, an increase in tenderness is observed as a result of enzymatic degradation of muscle tissue. This degradation is caused by proteolytic enzymes such as calpains and liposomal proteases. Temperature of storage can affect this enzymatic degradation, as well as other factors including: pH, amount and degree of cross-linking of connective tissue, and animal species. Koohmaraie (1996) suggested that ageing can be used to decrease shear force values during post-mortem storage.