Evaluation of Rigor Mortis in Tilapia Muscle by Rheological and Biochemical Properties

This research was carried out to clarify the initial point of rigor mortis that plays an important role in the delay of rigor mortis in a fish muscle from physical and biochemical viewpoints. The Bitou\u27s rigor index is used conventionally to evaluate the degree of rigor mortis in a fish body. But, this index did not necessarily agree with the rigor mortis in a fillet. The stress-relaxation test was applied to evaluate the rigor-mortis phenomenon in the fillet Theologically. On the other hand, K value, as biochemical freshness index, increased slowly in the muscle of fish which were killed immediately. Therefore, it was difficult to determine the accurate initial point of the rigor mortis. ATP (adenosine 5\u27-triphosphate) content of a fish muscle showed a sharp decrease at the initial point of rigor mortis. It was possible to judge the onset of rigor mortis from the speed change of ATP content