To study the drying characteristics of beef samples during freeze-drying process using a radiant heating, experiments were carried out at different sample surface temperatures with the freeze-drying apparatus reported in reference (2). The results obtained from these experiments and drying conditions were summarized as follows.<br>1. Schematic diagram of the radiant heating apparatus and the conditions of sample surface temperatares were shown in Fig. 1 and Table 1, respectively.<br>2. Experimental data were obtained in relation to the drying characteristics of the sample tested and the corresponding operating conditions during drying processes. The former consisted of the change in sample weight, calculated drying rate and sample temperatures while the latter included the heater and condenser surface temperatures as well as the total pressure in vacuum chamber. A result obtained for the sample number 15 was shown in Fig. 4. The changes in moisture contents, dimensions and densities of raw and dry samples, and the thermal conductivities of the dried region during 1st drying period (sublimation drying period) were presented in Table 2. The mathematical model (Fig. 3) proposed by Massey and Sunderland (1967) was used to measure the thermal conductivities. Typical sample weight and drying rate curves at various temperature conditions were shown in Fig. 5 and Fig. 6, respectively.<br>3. The equilibrium moisture contents (E. M. C.) were defined as the moisture contents of dry samples to the chamber pressures and the specimen temperatures at the end of drying process. The plots of E. M. C. against the specimen temperatures at the total pressure 0.31-0.57torr were shown in Fig. 7.<br>The maximum and minimum value of the E. M. C. were 5.3% w. b., 1.2% w. b., respectively. Rather great differences of the E. M. C. in low temperature range were attributed to the differences in the 2nd drying time.<br>4. Thermal conductivities of the dried region vs. the sample temperatures relationships were shown in Fig. 8. The results of this study obtained at the total pressure of 0.31-1.5torr were consistent with that reported by Massey and Sunderland, who had reported the conductivity of 0.055-0.075kcal/(mh°C) at 0.2-1.0torr. There was no evident effect of temperature level as indicated by Triebs et al. (1966), however, the thermal conductivity had tendency to decreace with the surface temperature over 60°C. This effect was interpreted in terms of the scorching of sample surface. The thermal conductivity in a direction perpendicular to the grain was substantially less than that parallel to the grain.