Rigor tensions and gaping in cod muscle

Summary The effects of temperature on the breaking stress and rigor tension of cod muscle fibres are described and related to the occurrence of gaping in fillets consequent on high temperature rigor mortis. This type of gaping is due to a combination of the greater rigor tensions generated at higher temperatures and the lowering of the inherent strength of the tissues; these effects proceed to such an extent that at elevated temperatures the muscle pulls itself to pieces. the magnitudes of the rigor tensions produced at a given temperature are similar whether or not the system is rendered anoxic. The results obtained are discussed in the light of published observations on the temperature dependence of cod fillet shrinkage and on the behaviour of mammalian muscle in similar situations. Attempts are also made to relate the size of the tensions that develop to the concentration at rigor, or changes in concentration between death and rigor, of lactate and adenosine triphosphate (ATP).