Marsh B B, Ringkob T P, Russell R L, Swartz D R, Pagel L A
Muscle Biology Laboratory, University of Wisconsin, 1805 Linden Drive, Madison, WI 53706, USA.
Meat Sci. 1987;21(4):241-8. doi: 10.1016/0309-1740(87)90061-1.
Electrical stimulation (ES) was applied at 500 V to one side from each of 60 beef carcasses at 30 to 40 min postmortem. Wide ranges of early-postmortem glycolytic and cooling rates were produced in the musculature by use of three different forms of ES (in addition to non-ES treatment of the contralateral sides) and application of chilling routines of four different degrees of severity. Panel and Warner-Bratzler shear evaluations of loin steaks from all 120 sides showed that tenderness was highest when glycolysis had proceeded at an intermediate rate (corresponding to the attainment of a 3-h pH of about 6·1) and was appreciably lower on both sides of this mid-value. The toughening effect of rapid glycolysis (relative to that of a moderately increased glycolytic rate) persisted through 14 days of aging at 2°C. These observations appear to be incompatible with the view that lysosomal enzymes contribute significantly to ES-induced tenderization. They also indicate that the effect of ES on tenderness is highly dependent on the subsequent cooling rate, very slow chilling sometimes accelerating the already high rate of pH fall to such an extent that the tissue is significantly toughened. Finally, they suggest that the goal of maximizing the early-postmortem rate of pH decline in bovine muscle is misguided and, if attained, will cause sub-optimal tenderness.
在宰后30至40分钟，对60头牛胴体的每一侧施加500伏的电刺激（ES）。通过使用三种不同形式的电刺激（对侧进行非电刺激处理）以及应用四种不同强度的冷却程序，在肌肉组织中产生了广泛的宰后早期糖酵解和冷却速率。对所有120个侧面的腰大肌牛排进行的感官评定和沃纳 - 布拉茨勒剪切力评估表明，当糖酵解以中等速率进行时（对应于3小时pH值达到约6.1），嫩度最高，在此中间值两侧的嫩度明显较低。快速糖酵解的 toughening 效应（相对于适度增加的糖酵解速率）在2°C下熟化14天的过程中持续存在。这些观察结果似乎与溶酶体酶对电刺激诱导嫩化有显著贡献的观点不一致。它们还表明，电刺激对嫩度的影响高度依赖于随后的冷却速率，非常缓慢的冷却有时会加速已经很高的pH下降速率，以至于组织明显变硬。最后，它们表明在牛肌肉中使宰后早期pH下降速率最大化的目标是错误的，如果实现，将导致次优嫩度。
