Effects of postmortem carcass electrical stimulation on goat meat quality characteristics

Abstract

Electrical stimulation (ES) has been reported to improve meat quality, but the effects of postmortem ES have not been fully characterized in goats. This experiment was conducted to determine the effects of postmortem ES on meat quality in two breeds of goats. Uncastrated Spanish and crossbreds (Boer × Spanish females × Kiko male) yearlings ( n = 10/breed, body weight 31.2 ± 2.43 kg) were transported to the slaughter facility, held overnight in pens without feed, and slaughtered on two different days. Immediately after slaughter each carcass was split into two halves along the vertebral column. The left half was subjected to a high voltage ES (580 V) at 5 s intervals during 120 s (treatment) and the right half was kept as a non-stimulated control. After 24 h of cooler storage (2 °C), the carcasses were fabricated into 2.5 cm-thick loin/rib chops. Longissimus dorsi (LD) muscle pH and temperatures were recorded at 0, 1, 2, 3, 4, 5, 6, 9, 12, 15, 18, and 24 h postmortem. The pH values of LD muscle were lower in stimulated sides than control sides ( P < 0.01), and pH decreased quadratically ( P < 0.01) with advancing time during the 24 h postmortem period. Treatment had no significant effect on the LD muscle temperature, and the temperature decline followed a cubic pattern ( P < 0.01) during the 24 h postmortem period. Muscle glycogen concentrations immediately after electrical stimulation (0 h) were lower ( P < 0.05) in the stimulated sides compared to control sides. Warner-Bratzler shear force (WBSF) values of loin chops were lower ( P < 0.01) in stimulated sides (3.0 kg) compared to control sides (4.2 kg), and the chops from Spanish goats (3.9 kg) had higher ( P < 0.05) WBSF values compared with crossbreds (3.3 kg). Color values ( L*, a*, b*, chroma, and hue angle) and sarcomere length were not affected by ES or breed. Heated calpastatin activities were not influenced by ES, but the activities were lower at day 4 compared with day 1 of aging ( P < 0.05). There were no significant effects ( P > 0.05) of ES or aging time on selected myofibrillar protein concentrations (myosin heavy chain, myomesin, desmin, actin, troponin-T, and myosin light chain, P > 0.05). However, desmin concentration tended to decrease at day 4 of aging ( P = 0.08). The results indicate that ES significantly accelerated postmortem glycolysis and improved tenderness of loin chops, as indicated by WBSF values.