Effects of low-voltage electrical stimulation and rapid chilling on meat quality characteristics of Chinese Yellow crossbred bulls.

In this study, the effects of low-voltage electrical stimulation (LVES) and rapid chilling (RC) treatments on the quality characteristics of beef carcasses were evaluated, including the rate of pH and temperature decline, evaporative loss of carcasses, purge loss, cooking loss, and shear force values of m. longissimus steaks. Each carcass of 28 Chinese Yellow crossbred (SimmentalxYanbian) bulls was subjected to one of the four treatments, i.e., electrical stimulation and conventional chilling (ES/NR), electrical stimulation and rapid chilling (ES/RC), no electrical stimulation and rapid chilling (NE/RC), or no electrical stimulation and conventional chilling (NE/NR). Carcass pH and temperature were measured at 1, 3, 5, 7, 9, 11, and 24h post-mortem. After that, a 2.5-cm-thick m. longissimus steak was taken from the right side of each carcass and used for analyses of purge loss, cooking loss and Warner-Bratzler shear force (WBSF). The results showed that LVES accelerated the rate of carcass pH decline (P<0.05) and rapid chilling increased the rate of carcass temperature decline (P<0.05). There was no significant difference found for the mean carcass evaporative losses from all treatments (P>0.05). Mean purge losses for m. longissimus steaks from rapidly chilled carcasses were lower (P<0.05) than those from conventionally chilled carcasses. Electrical stimulation had no impact on m. longissimus steak purge losses (P>0.05). Rapid chilling significantly decreased (P<0.05) the cooking loss of m. longissimus steaks from electrically stimulated carcasses whilst it increased the cooking loss of m. longissimus steaks from carcasses without stimulation (P<0.05). LVES increased (P<0.05) cooking loss of m. longissimus steaks from conventionally chilled carcasses, but had no effect under the procedure of pre-rigor rapid chilling (P>0.05). The lowest mean shear force value was found for the ES/NR-treated m. longissimus steaks, whilst the highest one for the NE/RC-treated carcasses (P<0.05). Regression analyses indicated that carcass pH at 1h post-mortem was the most useful predictor for beef shear force. Abattoirs processing Chinese Yellow bulls could optimize meat quality by using low-voltage stimulation together with pre-rigor rapid chilling.