Effect of Heating Rate on Shortening of Prerigor Chicken Breast Muscle

Abstract Experiments were conducted to evaluate the effects of various heating rates on prerigor chicken breast muscle (Pectoralis major). Heating rates from 2 C per 6 min to 2 C per 18 min (Experiment 1) gave similar results in percentages of myofibrillar, cooking, and total shortening. Myofibrillar shortening began at approximately 39 C and completed at 46 to 50 C, and cooking shortening began at 65 to 66 C, regardless of heating rate. Heat absorbed per gram of muscle sample to onset and completion of myofibrillar shortening, or to onset of cooking shortening, was not different for the various heating rates. A higher muscle temperature at both onset and completion of myofibrillar shortening was observed at the 2 C per 2 min heating rate than at the 2 C per 12 min heating rate (Experiment 2). At 2 C per 2 min, myofibrillar shortening was more extensive, occurred faster, and was coincident to the absorption of more heat per gram of muscle to onset and completion as compared to 2 C per 12 min. The results support the view that rapid heating (≥2 C per 2 min) of prerigor muscle elicits extensive shortening caused by an active contraction.