Resumen de Development of Muscle Thermal Rigorometer and Characterization of Heat-induced Muscle Shortening of Tilapia
A muscle thermal rigorometer was constructed, allowing muscle shortenings induced by dynamic heating or isothermal aging to be monitored. Operating isothermally like a traditional rigorometer at 10 °C, postmortem dorsal muscle shortening (S10°C) developing from 0% to 10% of its initial length in corresponding to RIfiber along fiber-direction developing from 0% to 100% within 16 h was monitored for freshwater tilapia. Monitoring meat cooking in the dynamic heating mode, heat-induced shortenings could be observed for all muscle samples possessing different degrees of rigor induced by 10°C aging. The heat-induced shortening (Sdynamic) plus its 10°C aging shortening (S10°C) for each sample was the same, Soverall= S10°C+ Sdynamic= 10%. Their heat-induced shortening peak temperatures (Ts) from 30°C to 48°C were inversely correlated with the sample RIfiber from 0% to near 100%. These findings together with an additional calcium/adenosine triphosphate (ATP) model studies showed that the ATPase related myofibrillar contractile system was responsible for these low-temperature cooking shortenings, which along with Ts values could thus be adopted as new rigor indices.
