Thermophysical Properties of Beef Steaks Varying in USDA Quality Grade and Internal Temperature

The objectives of this study were to determine the influence of quality grade and internal temperature on the thermophysical properties of beef strip steaks. Beef strip loins (n=24) were collected from USDA Prime (PR), Low Choice(LC), and Standard (ST) carcasses. Strip loins were fabricated into 2.54 cm steaks at 21 d postmortem and randomly assigned to an internal temperature (4°C, 25°C, 55°C, 60°C, 71°C, 77°C). Steaks were subjected to various thermal and physical property measurements. No quality grade × internal temperature interaction was observed for diffusivity and conductivity (P > 0.05). Steaks tempered to 25°C had the greatest conductivity compared with all other internal temperature treatments (P = 0.021). A quality grade×internal temperature interaction was observed for center myosin and sarcoplasmic protein enthalpy values (P < 0.001). Raw (4°C and 25°C) ST steaks had lower enthalpy values compared with raw PR and LC steaks (P < 0.05). Raw steaks had greater surface myosin and both center and surface actin enthalpy values (P < 0.05). A quality grade × internal temperature was observed for surface and center viscoelasticity (P < 0.05). Raw steaks possessed less elastic behavior compared with cooked steaks, regardless of quality grade (P<0.05). Quality grade and internal temperature impacted expressible moisture and water holding capacity (P ≤ 0.001). ST steaks possessed increased expressible moisture and water holding capacity compared with LC and PR steaks (P<0.05). A quality grade×internal temperature was observed for Warner-Bratzler shear force and springiness (P ≤ 0.008). Internal temperature impacted all texture profile analysis attributes (P < 0.05). PR steaks were more cohesive than ST steaks (P = 0.011). These data show that final internal temperature and USDA quality grade impact thermophysical properties of beef steaks