Hannula Tapio, Puolanne Eero
Department of Food Technology, University of Helsinki, P.O. Box 27, Viikki E, FIN 00014 Helsinki, Finland.
Meat Sci. 2004 Jul;67(3):403-8. doi: 10.1016/j.meatsci.2003.11.012.
To study the effects of cooling regime on beef tenderness, seven commercial beef slaughterhouses with different cooling regimes were selected to obtain different carcass cooling rates. The pH values and temperatures of 8 M. longissimus dorsi (LD) and M. semimembranosus (SM) muscles from each slaughterhouse were monitored for 30 h. The muscles of the monitored carcasses were excised and vacuum packed for Allo-Kramer shear force (SF) determinations. Samples were kept at 3-4 °C for 5 or 21 d. The slaughterhouses were grouped by their average pH values of the muscles, prevailing at the moment when the temperature of the muscles reached 7 °C. The pH groups for LD were (i) low (5.52-5.63), (ii) medium (5.84-5.97) and (iii) high (6.16-6.17). The highest shear forces were in group (iii), being the toughest: 155-152 N/g, and the lowest in group (i) (the most tender): 108-116 N/g, respectively. The regression equation or the shear force was SF=-295.4+73.0∗(pH at 7 °C); (R(2)=87%). There was no significant correlation between the cooling rate and tenderness in SM, indicating that it is difficult to control the tenderness of all muscles using the same cooling regime. The ageing effect was more marked and the variation in the shear forces smaller in the slaughterhouses generating carcasses with low pH values at 7 °C than in those generating high ones. It was concluded that a low cooling rate, or more specifically, the temperature/pH at the onset of rigor mortis, is important for beef tenderness. The pH of LD must fall to values below 5.7 before/when the temperature reaches 7 °C.
为了研究冷却方式对牛肉嫩度的影响，选择了 7 家具有不同冷却方式的商业牛肉屠宰场，以获得不同的胴体冷却速率。监测每个屠宰场的 8 块 M.长肌（LD）和 M.半腱肌（SM）肌肉的 pH 值和温度 30 小时。监测胴体的肌肉被切除并真空包装，用于 Allo-Kramer 剪切力（SF）测定。样品在 3-4°C 下保存 5 或 21 天。根据肌肉达到 7°C 时的平均 pH 值，将屠宰场分组。LD 的 pH 组为（i）低（5.52-5.63）、（ii）中（5.84-5.97）和（iii）高（6.16-6.17）。剪切力最高的是第（iii）组，最坚韧：155-152 N/g，最低的是第（i）组（最嫩）：108-116 N/g。剪切力的回归方程为 SF=-295.4+73.0∗(7°C 时的 pH 值)；(R(2)=87%)。SM 的冷却速率与嫩度之间没有显著相关性，表明使用相同的冷却方式很难控制所有肌肉的嫩度。在产生 7°C 时 pH 值较低的胴体的屠宰场中，老化效应更为明显，剪切力的变化较小，而在产生 pH 值较高的胴体的屠宰场中则变化较大。研究结果表明，较低的冷却速率，或者更具体地说，僵直开始时的温度/pH 值，对牛肉嫩度很重要。在温度达到 7°C 之前/之后，LD 的 pH 值必须降至 5.7 以下。
