THE INFLUENCE OF TEMPERATURE ON BROILER BREAST MUSCLE SHORTENING AND EXTENSIBILITY

The purpose of this study was to characterize the influence of tempera ture on muscle shortening and extensibility in broiler breast muscle ( Pectoralis major). The extent of prerigor muscle shortening has been s hown to affect the ultimate tenderness of meat, whereas a decrease in extensibility has traditionally been used to define rigor mortis in mu scle. Muscle shortening over time was determined at three incubation t emperatures: 0, 23, and 41 C. Shortening was measured on intact and ex cised muscles, as well as on muscle strips with and without attached w eight (200 g). The time a muscle strip needed to reach loss of extensi bility was also determined at each of the three incubation temperature s. The intact and excised muscles showed some evidence of both cold an d rigor (hot) shortening. No extreme shortening effects were found in the muscle strips incubated with or without attached weight. The use o f muscle strips to predict intact muscle or excised whole muscle short ening in a complex muscle such as poultry Pectoralis may be limited. T he time required to loss of extensibility of the muscle strips, i.e., rigor completion, was 5.5, 4.5, and 0.8 h at 0, 23, and 41 C, respecti vely. The results show that cold-induced shortening may contribute to toughening of early deboned broiler breast muscle, but its impact on c ommercial processing and subsequent meat tenderness does not appear to be consistent.