Effects of concentration and temperature on the thermophysical properties of Clarified Pomegranate Juice

Determination of thermo-physical properties of pomegranate juice is necessary to control processes such as drying and concentration. These properties have been affected by soluble solid content and temperature. Therefore the properties including; density، specific heat and thermal conductivity were determined at three levels of soluble solid content، 12o، 40o and 65o Brix and temperature range from 25 to 70 oC. Thermal conductivity by co-axial cylinder apparatus، specific heat by differential scanning calorimeter and density by a volumetric pycnometer were measured. Regression analysis indicated that both soluble solid content and temperature affected on these properties but the soluble solid content has more influence. Increase of soluble solid content from 12 to 65 caused a decrease in thermal conductivity from 0. 233 to 0. 193 W/m. oC، specific heat from 5. 19 to 3. 34 kJ/kg. oC and an increase in density from 1027 to 1323 kg/m3 respectively. With increase in temperature from 30 to 70 oC، density decrease from 1173 to 1150 kg/m3 but thermal conductivity increase from 0. 188 to 0. 229 W/m. oC during temperature increasing from 28 to 42 oC and specific heat increase from 3. 9 to 4. 4 kJ/kg during temperature increasing from 40 to 60 oC. With regression analysis، the suitable empirical models of thermophysical properties of pomegranate juice with operating variables were obtained.