Measurement of coefficients for simultaneous heat and mass transfer in food products

Two experimental devices were designed and built to determine four coefficients K_T, K_M, D_M and D_T (or δ_T=D_T/D_M) occurring in simultaneous heat and mass transfer equations, where, K_T and D_M are thermal conductivity and moisture diffusivity, respectively, D_T (or δ_T) is temperature gradient induced moisture migration coefficient and K_M is moisture gradient induced heat transfer coefficient. Three food materials, i.e., potato, bread dough and bread, were tested. From this study, it was found that the value of δ_T was higher for low density food materials, such as bread, than for high density materials, such as potato. The coefficient δ_T measures moisture migration contribution due to temperature gradient within the material. The average values of δ_T for potato, bread dough and bread were 0.0014, 0.0059 and 0.0127 per °C, respectively. The contribution of temperature gradient to the overall moisture migration is negligible in high density materials. However, this contribution may be important in the moisture migratlon analysls for low density materials. The molsture gradient induced heat transfer coefficient was found to be negligible for the materials tested in this study.