Thermal transitions of king fish whole muscle, fat and fat-free muscle by differential scanning calorimetry

Thermal transitions of whole king fish (Scomberomorus commerson) muscle, fat and fat-free muscle were measured by differential scanning calorimetry. Initial freezing points were measured by cooling curve method and modeled as a function of solids content with the Chen equation. The muscle showed thermal transitions. However, it was difficult to justify that it was glass transition of whole or fat-free fish muscles. The end point of freezing and corresponding solids content was estimated to be -17.4 °C and 68.8%, respectively. The unfreezable water content was estimated as 36.7%. Adsorption isotherms of fish muscle were measured at room temperature by the isopiestic method and data were modeled with BET and GAB equations. The BET monolayer values were found as 3.6 and 4.8% (dry basis) for whole and fat free muscle. The data obtained could be useful in the efficient design of freezing and drying processes and also in the evaluation of chemical and biochemical stability of fat and free fatty acids in fish muscle.