The effect of electrical stimulation on beef tenderness, protease activity and myofibrillar protein fragmentation.
From six one-year-old White red bulls, one randomly assigned carcass half was subjected to high voltage electrical stimulation (HVES) at 1 h post morten (pm). Longissimus dorsi (LD) steaks from control (C) and stimulated sides (ES) were removed at 24 h pm, stored at 4 degrees C and sampled at 1, 6, 8 and 12 days pm. HVES caused an immediate fall of pH with about 0.5 units (P less than 0.01), and an increase in temperature of about 1 degree C (P less than 0.05). HVES lowered LD shear force values (P less than 0.05), both at 1 and 8 days pm. Sarcomere length was not affected by stimulation, but cooking losses were increased in ES. Semi-quantitative SDS-PAGE, using BSA as internal standard showed the rate of degradation of several myofibrillar proteins to be increased by HVES. Levels of 43-kDa peptide increased upon ageing and were higher in ES (P less than 0.001). The level of 30-kDa peptide increases strongly in the early ageing period and faster in ES. It is striking that 1 h pm ES contain more 30 kDa (P less than 0.05), suggesting activation of calpain 1. The increase upon ageing in levels of 34- and 35-kDa peptides, often considered as the tropomyosins, suggests that these compounds are myofibrillar degradation products. Troponin-T (TNT) was degraded very fast in the early ageing period. The degradation rate was increased by HVES (P less than 0.005) and related to rate of tenderization (r = 0.90).(ABSTRACT TRUNCATED AT 250 WORDS)
Uytterhaegen
L
L
Research Center for Nutrition, Animal Production and Meat Technology, State University of Ghent, Belgium.
Claeys
E
E
Demeyer
D
D
D000818:Animals; D002154:Calpain / Q000378:metabolism; D002401:Cathepsin B / Q000378:metabolism; D002417:Cattle; D004558:Electric Stimulation; D010450:Endopeptidases / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008297:Male; D008460:Meat; D008970:Molecular Weight; D009124:Muscle Proteins / Q000378:metabolism*; D009210:Myofibrils / Q000378:metabolism* / Q000648:ultrastructure; D010446:Peptide Fragments / Q000378:metabolism; D011180:Postmortem Changes; D012518:Sarcomeres / Q000648:ultrastructure; D014336:Troponin / Q000378:metabolism; D020107:Troponin T
D009124:Muscle Proteins; D010446:Peptide Fragments; D014336:Troponin; D020107:Troponin T; D010450:Endopeptidases; D002154:Calpain; D002401:Cathepsin B