排酸牛肉的品质变化规律及其烹煮时机的优选

Analysis of quality changes and preferred choice of cooking time of beef during aging

为探究排酸牛肉的品质变化规律,并指导合理烹饪,将中国西门塔尔牛背最长肌在4℃条件下分别排酸12、24、48、72、120、168 h,对排酸期间牛肉的细菌总数、挥发性盐肌氮(thiobarbituric acid reactive substances,TVB-N)、硫代巴比妥酸值(total volatile basic nitrogen,TBARS)等新鲜度指标,以及剪切力、肌原纤维小片化指数(myofibril fragmentation index,MFI)、加压失水率、僵直指数、蛋白质热性质等品质指标进行测定与分析。结果表明,排酸168 h的牛肉细菌总数、TVB-N和TBARS值虽有明显上升,但仍处于新鲜肉的数值范围内,肌肉色泽良好,新切面湿润。排酸72、120、168 h的牛肉剪切力、加压失水率、僵直指数均降低明显(P<0.05),MFI值显著增加(P<0.05),此阶段肌肉骨架蛋白发生降解,牛肉嫩度得到极大改善,保水性提高。排酸24、48 h牛肉肌球蛋白的热变性温度较高,肌肉中形成大量难以解离的肌动球蛋白,随后变性温度有明显下降(P<0.05),肌肉热稳定性降低。因此,从改善肌肉品质和提高加热效率的角度出发,可选择排酸72~168 h作为牛肉较优的烹煮时机。

In order to explore changes in quality of aged beef,and to guide the rational cooking,the longissimus dorsi of Chinese Simmental cattle were aged for 12,24,48,72,120 and 168 hours at 4℃.Freshness indicators such as the total number of bacteria,total volatile basic nitrogen(TVB-N),thiobarbituric acid reactive substances(TBARS),and quality indicators such as shearing force,myofibril fragmentation index(MFI),pressure loss rate,stiffness index,protein thermal properties were determined and analyzed.Results showed that the total number of bacteria,TVB-N and TBARS values of beef aged for 168 hours were significantly increased,but it was still within the range of fresh meat and showed good color and wet new-cut surface.The shearing force,pressure loss rate and stiffness index of beef aged for 72,120 and 168 hours were significantly reduced(P<0.05),and MFI value were significantly increased(P<0.05);the muscle matrix protein was degrading;the tenderness and water retention of beef were improved at this stage.Because a large amount of actomyosin formed and was difficult to dissociate,heat denaturation temperature of myosin of beef aged for 24 and 48 hours was high,but the thermal stability of muscle decreased significantly(P<0.05)with an extension of aging time.Therefore,from the perspective of improving muscle quality and heating efficiency,it was reasonable to select beef aged for 72 to 168 hours as the preferred cooking time.