Effect of к-carrageenan and NaCl on thermal properties of frozen surimi prepared from Adriatic pilchard

Abstract

Samples of surimi were prepared under laboratory conditions from Adriatic pilchard ( Sardina pilchardus). Water content in surimi was 81.5% before mixing with NaCl and к-carrageenan, which were added in the range of mass fraction from 0 to 10%. Relative apparent specific enthalpy ( H-), initial freezing point T i, density p and thermal conductivity k of surimi in the temperature range from -25 °C to 10 °C were determined by differential thermal analysis (DTA), gravimetric method and line-heat source technique, respectively. For determination of relative apparent specific enthalpy ( H-) the mathematical model of enthalpy based on orthogonal collocation approximation of DTA was applied. Redistributions of apparent enthalpy in the freezing range as functions of mass fractions of added substances were determined. Increase of mass fraction of added substances resulted in the increase of mass fraction of bound (unfreezable) water and lowered initial freezing point Ti, which has effects on the decrease of therma...