The influence of temperature on broiler breast muscle shortening and extensibility

The purpose of this study was to characterize the influence of temperature on muscle shortening and extensibility in broiler breast muscle (Pectoralis major). The extent of prerigor muscle shortening has been shown to affect the ultimate tenderness of meat, whereas a decrease in extensibility has traditionally been used to define rigor mortis in muscle. Muscle shortening over time was determined at three incubation temperatures: 0, 23, and 41 C. Shortening was measured on intact and excised muscles, as well as on muscle strips with and without attached weight (200 g). The time a muscle strip needed to reach loss of extensibility was also determined at each of the three incubation temperatures. The intact and excised muscles showed some evidence of both cold and rigor (hot) shortening. No extreme shortening effects were found in the muscle strips incubated with or without attached weight. The use of muscle strips to predict intact muscle or excised whole muscle shortening in a complex muscle such as poultry Pectoralis may be limited. The 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, respectively. The results show that cold-induced shortening may contribute to toughening of early deboned broiler breast muscle, but its impact on commercial processing and subsequent meat tenderness does not appear to be consistent.