Effects of ultrasound and convection cooking to different end point temperatures on cooking characteristics, shear force and sensory properties, composition, and microscopic morphology of beef longissimus and pectoralis muscles.

Longissimus and pectoralis muscles were removed from 10 steer carcasses at 4 d postmortem, aged for 14 d at 2 degrees C, then assigned to either ultrasound or convection cooking to either 62 degrees C or 70 degrees C internal end point temperature. During cooking, time-temperature profiles and energy consumption were monitored. Ultrasound cooking resulted in greater (P < .05) cooking speed, greater (P < .05) moisture retention and less (P < .05) cooking loss, greater (P < .05) efficiency of energy consumption, a more uniform cooking environment, and less (P < .05) instrumental peak-force work to shear muscle samples than convection cooking. The ultrasound treatment also resulted in a reduction (P < .05) in soluble collagen content and superior (P < .05) myofibrillar tenderness, as determined by a trained sensory panel, than convection cooking. Electron micrographs indicated that ultrasound-cooked muscles had longer sarcomeres, larger diameter fibers, and more myofibrillar disruption and shattering. Longissimus muscles cooked faster (P < .05) and more (P < .05) energetically efficient, had less (P < .05) total collagen, and were superior (P < .05) in instrumental evaluated texture and sensory tenderness than pectoralis muscles. Cooking to 70 degrees C caused greater (P < .05) moisture and cooking losses, required more (P < .05) time and energy input to cook, and negatively (P < .05) affected instrumental textural and sensory tenderness characteristics. Electron micrographs indicated a shortening of sarcomeres, more deterioration of the banding structure, reduction in fiber diameter, and breakdown of endomysial and perimysial connective tissue at an internal temperature of 70 degrees C vs 62 degrees C. This research identifies ultrasound cooking as a new, rapid, energy-efficient method that may improve some meat textural attributes.