Electrical impedance and tenderisation in bovine meat

The electrical properties and the muscle fibre mechanical resistance of different beef muscles were measured between 1 and 14 days post-mortem. Electrical measurements used different electrode types working by contact with or penetration of muscle. Measurements from the different electrode types were strongly correlated (0.83< r2 <0.96). Both impedance (Z) and the ratio Z1 kHz/ Z100 kHz decrease during ageing. These parameters show an almost linear relationship with muscle fibre mechanical resistance. However, the slope of these curves for one muscle changed among animals. Therefore, these electrical parameters are not useful for the prediction of the state of ageing. Meat electrical anisotropy decreases both when frequency increases and with ageing. Electrical anisotropy measured at 1 kHz is significantly (r=0.59, N=129 P<0.01) correlated to muscle fibre mechanical resistance. The mean anisotropy decreases linearly with muscle fibre mechanical resistance in the same way for Semimembranosus and Pectoralis Profundus muscles. When meat is fully aged it is almost electrically isotropic. Electrical anisotropy is, therefore a potential parameter to evaluate meat ageing, but improvements in accuracy are needed before it can be used.