WANG Hengpeng, WANG Yinlan, WU Peng, CHEN Shengsu, TU Mingliang, Gao Ziwu, MENG Xiangren
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.