The effect of electrical stimulation on post mortem myofibrillar protein degradation and small heat shock protein kinetics in bull beef

This study aimed to determine the effect of electrical stimulation and ultimate pH (pHu) on shear force, myofibrillar protein degradation and small heat shock proteins (sHSP) concentrations in M. longissimus lumborum (LL). The LL from both sides of carcasses (n = 15) was excised with low voltage electrical stimulation (ES) applied to an LL muscle from one side, while the opposing LL muscle was not stimulated (NS). Muscles were categorised into low (pHu < 5.8), intermediate (5.8 ≤ pHu < 6.2) and high pHu (pHu ≥ 6.2) and aged for up to 28 days post mortem at -1.5°C. High pHu meat tenderised faster which corresponded with the faster degradation of titin and desmin in this group compared with low and intermediate pHu meat. Electrical stimulation significantly affected the kinetics of αβ-crystallin, HSP20 and HSP27 with higher concentrations of these sHSP in ES muscles at latter ageing timepoints compared with NS muscles.