Investigating the Effect of Different Factors on Thermal Conductivity and Specific Heat of Pumpkin Puree

For the precise designing of thermal processes, determination of thermal properties of foods is necessary. The specific heat and thermal conductivity are the two main thermal properties of food products.

In this research, the thermal properties of pumpkin purée in five levels of moisture (25, 30, 35, 40 and 45 percent), five temperature levels (25, 35, 45, 50 and 55ºC), different percentages of salt (0, 0.5, 1, 1.5 and 2%) and different percentages of sugar (0, 10, 15, 20 and 25%) were investigated.

The experiments showed that temperature and moisture caused increases in specific heat and thermal conductivity in pumpkin puree whereas the addition of salt and sugar caused reductions in both specific heat and thermal conductivity of pumpkin puree. In order to predict the effect of moisture, temperature, salt and sugar content on thermal properties of pumpkin puree, regression modes are used. Coefficient of Determination (R2) of specific heat capacity for temperature, moisture content, salt content and sugar content were 0.920, 0.941, 0.949 and 0.961, respectively. Coefficient of Determination (R2) of thermal conductivity for temperature, moisture content, salt content and sugar content were 0.851, 0.962, 0.956 and 0.979, respectively.

Temperature and moisture content have direct effect on thermal properties while salt and sugar contents have reverse effect on thermal properties of pumpkin puree.