Kinetic study on the thermal denaturation of protein in yellowfin tuna meat

Abstract

The purpose of this work was to study the kinetics of thermal denaturation of protein in
tuna meat. Fresh yellowfin tuna meat was sealed into a stainless steel differential scanning
calorimetry (DSC) pan, and subsequently heated at 45, 50, 60 and 65 °C for various interval
time. The residual enthalpy of fresh and the heated tuna meat was determined by DSC at
scanning rate 5 °C/min. The residual enthalpy of fresh tuna meat was used as a reference
in calculation of denaturation degree. DSC thermogram of fresh tuna meat showed four
denaturation peaks at 41, 49, 58 and 67 °C. It was suggested that first two peaks represented
for myosin fractions, and the others are sarcoplasmic proteins and actin, respectively. The
plot between logarithm of degree of denaturation and heating time revealed that there were
two first-order rate constants for each heating temperature. This implied that there might
be two mechanisms of protein denaturation in tuna meat. The mechanisms of these thermal
denaturations probably come from the non-aggregated or reversible state and the stage of
protein aggregation.