高压和氯化钙结合处理对牛肉嫩度的影响

为探明高压和氯化钙（CaCl2）注射结合处理对僵直后期牛肉嫩度的影响，首先分别对CaCl2浓度、高压强度及保压时间对宰后36?h的牛背最长肌嫩度的影响进行分析，在3个单因素试验的基础上，采用Box-Behnken响应曲面中心组合设计法，对高压和CaCl2结合处理嫩化牛肉的工艺参数进行优化，并通过透射电镜对肌纤维的超微结构进行分析。结果表明：以CaCl2浓度、高压强度和保压时间为自变量，剪切力值为响应值，得到的二次多项式回归模型拟合度高（决定系数R2=0.9742）；高压强度、保压时间、CaCl2浓度、高压强度和保压时间的交互作用对牛肉嫩化效果极显著（P＜0.01），高压强度和CaCl2浓度的交互作用对牛肉嫩化效果显著（P＜0.05）。高压和CaCl2结合处理嫩化牛肉最佳工艺为：高压强度241?MPa，CaCl2浓度0.24?mol/L（样品质量5%的注射量），保压时间14?min。应用此工艺嫩化牛肉，和对照相比牛背最长肌剪切力值下降了52.98%，肌纤维间隙增大，肌节完整性遭受破坏，牛肉嫩度明显改善。

Effects of combined high pressure and calcium chloride treatment on beef tenderness

This experiment was performed to investigate the effects of combined treatment of high pressure and calcium choride(CaCl2) injection on post-rigor beef tenderness. Initially, samples from beef longissimus dorsi after 36 h post-slaughter were removed and the influences of CaCl2 concentration, high pressure level and high pressure processing time on beef tenderness were analyzed respectively. On the basis of the three single-factor experiments, the Box-Behnken response surface methodology was applied to optimize beef tenderization parameters. Meanwhile, the modifications of ultrastructure were observed with transmission electron microscope (TEM). The results indicated that the response surface model, with CaCl2 concentration, high pressure level and processing time being independent variables and shear force being responses, was highly fitted (R2=0.9742). Beef tenderness was significantly influenced by high pressure level, processing time, CaCl2 concentration, high pressure level × processing time (p<0.01), and high pressure level × CaCl2 concentration (p<0.05). The optimum tenderization parameters of combined high pressure and calcium chloride treatment were as follows: high pressure level was 241 MPa, CaCl2 concentration was 0.24 mol/L (with 5% injection of sample weight), processing time was 14 min, under which conditions, the shear force value of beef longissimus dorsi was declined by 52.98%, and intermyofibrillar space was enlarged, meanwhile the integrity of sarcomeres was destructed, and the tenderness was significantly improved.