5.1. Assay of thermal conductivity of guava fruit
Variation of thermal conductivity at different instant of time in the range of 40% to 80% (wb) moisture content for densities of 911 kg/m3 (D1) and 1062 kg/m3 (D2) are depicted in Figs. 2 and 3. It is observed that at all moisture contents, thermal conductivity of guava fruit increases with increase in time. But at lower moisture levels Thermal conductivity is relatively low with higher moisture levels with increase in temperature or time. Because, as the moisture evaporates the sample shrinks and the rate of shrinkage in the initial stage of heating is more, leading to porosity i.e. entrapped air which is a bad conductor of heat, hence decrease
in the thermal conductivity [17,18].