THERMAL CONDUCTIVITY MODELLING OF FREEZE DRIED SEA BREAM FILLETS AS A FUNCTION OF TEMPERATURE AND MOISTURE CONTENT

For design and evaluation of food processes in which conductive heat is involved reliable values of thermal conductivity k are required. These values depend on the temperature and the composition of the food. Fresh as well as rehydrated freeze dried sea bream fillets with water content ranging from 2 to 46 g H₂O/100 g dry base were measured at temperatures from 0-25°C. The k-values of these fillets were measured with the line source probe method and ranged from 0.078W/mK to 0.125W/mK for the rehydrated fillets and up to 0.512W/mK for the fresh fillets. Thermal conductivity increased linearly with increasing moisture and exponentially with increasing temperature. A multi-parameter model was developed to predict the values of k of sea bream fillets at any combination of water content and temperature. The parameters of the model were estimated using non-linear regression and the predicted from the model k-values were in good agreement with the k-values obtained from the measurements.