Thermal stability of fish myofibrils: a differential scanning calorimetric study

Abstract

SummaryThe variation in myofibrillar protein thermostability was compared for various fish species, using differential scanning calorimetry. The tropical fish, catfish (Clarius gariepinus), carp (Cyprinus carpio), Nile perch (Lates niloticus), red snapper (Lutianus sebae), red mullet (Parpeneus barberinus), sea bream (Gymnocranius rivalatus), and cold‐water reared trout (Salmo gairdneri) and cod (Gadus morhua) were analysed. Onset temperature of myofibrillar protein denaturation occurred at up to 11°C higher for tropical species (43.5°C, catfish), than cod (32.6°C) at pH 7 and low ionic strength (I). As pH (6.0‐8.0) and I (0.05‐1.00) were increased, thermal denaturation temperatures of myosins from tropical, but not cold‐water, species decreased. Enthalpies of myofibrillar denaturation decreased for all species with increasing pH and I. Only one thermal transition was detected for myosin at pH 6 and low I, increasing to three as pH and I were increased. Changes in thermal characteristics of myosin subunits over iced and frozen storage suggest more rapid deterioration in cold‐water than in tropical fish. The differences in myofibrillar stability of fish from different habitat temperatures have implications for the processing and storage of tropical fish.