EFFECT OF HYDRODYNAMIC PRESSURE PROCESSING AND AGING ON THE TENDERNESS AND MYOFIBRILLAR PROTEINS OF BEEF STRIP LOINS

This study evaluated the effects of hydrodynamic pressure (HDP) processing and aging on the tenderness and myofibrillar proteins of beef strip loins. Loins (n = 12) were halved at 48 h postmortem and assigned to HDP or control treatments. Following treatment, each half was divided into three portions for aging (0, 5 or 8 days). Samples were removed for Warner–Bratzler shear force (WBSF) determination and myofibrillar protein isolation. HDP decreased (P < 0.0001) WBSF values 23% at 0, 5 and 8 days of aging. Myofibrillar fragmentation and myofibrillar protein solubility increased (P < 0.01) with HDP and aging. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting analysis of myofibrillar proteins showed that HDP and aging decreased the intensity of the troponin T (TnT) band and enhanced the accumulation of the 30 kD TnT degradation product. These data suggest that HDP is more effective than aging tenderization, and that HDP tenderization is caused by both protein degradation and physical disruption of the myofibril apparatus. PRACTICAL APPLICATIONS Hydrodynamic pressure (HDP) processing was shown to instantaneously tenderize tough cuts of beef to tenderness levels attained following 8 days of postmortem aging. For the meat industry, these results demonstrate the potential benefits of alternative tenderization techniques, such as high-energy shock waves. Observed changes in protein characteristics due to HDP and aging allow researchers to understand better potential mechanisms of meat tenderization.