Influence of moisture content on thermophysical properties of enzyme clarified sapota (Achras sapota L.) juice

Investigation was carried out to evaluate thermophysical properties such as density, Newtonian viscosity, thermal conductivity, specific heat and thermal diffusivity of enzyme clarified sapota (Achras sapota L.) juice at different moisture contents ranging from 38.01% to 88.64% (wet basis) corresponding to a water activity in the range of 0.839 to 0.987. The investigation showed that density and Newtonian viscosity of enzyme clarified sapota juice decreased significantly (p 0.05) with increase in moisture content as well as water activity, whereas thermal conductivity increased significantly (p 0.05) with increase in moisture content and water activity. The specific heat and thermal diffusivity were markedly affected by moisture content as well as water activity. Empirical mathematical models were established relating to thermophysical properties of enzyme clarified sapota juice with moisture content/water activity. Results indicated that there was a high significant (p 0.0001) correlation between thermophysical properties with moisture content/water activity of enzyme clarified sapota juice. A significant (p 0.0001) positive correlation between thermal properties and moisture content/water activity, whereas significant (p 0.00001) negative correlation between physical properties with moisture content/water activity was observed. In general, the thermophysical properties of enzyme clarified sapota juice were markedly affected by moisture content/water activity.