The effect of electrical stimulation on the quality of three bovine muscles

Meat bulls were randomly assigned to five treatment groups-intermittent electrical stimulation at 300 V (ES) at 5 min and 35 min post mortem (intact carcasses), 35 min post mortem (split carcasses) and non-stimulated controls (NS) (intact and split carcasses). Stimulated carcasses in all groups showed a significantly more rapid pH fall during the first 8h post mortem in adductor (AD), longissimus dorsi (LD) and triceps brachii (TB) muscles. Cooling rates were relatively slow. Samples were removed from the carcass at 24h post mortem. After vacuum storage at 3°C for 6 days stimulated muscles showed lower drip (LD and TB) and heating loss (TB), lower shear force values (AD, LD and TB) and higher taste panel scores (AD, LD and TB) compared with NS controls. No significant differences in tenderness were observed between the three ES groups. Sarcomere length assessment showed more contraction in NS carcasses, particularly in the superficially located LD and TB. These results suggest that cold shortening may occur in some muscles under cooling conditions so far considered safe in this respect. Since higher drip losses coincided with lower sarcomere lengths in these (NS) muscles, it is suggested that, under these conditions, ES may mask the increased drip losses which are possibly the result of muscle contraction. Furthermore, ES prevents the occurrence of cold shortening and, in addition, may exert some 'extra tenderising effect', which is not related to splitting of the carcass nor restricted merely to the LD muscle.