ミソペーストの凍結乾燥条件と移動物性値に関する研究

抄録

Drying Characteristics and the transport properties have been measured for the dried layers of 9.6-28.8% miso paste undergoing freeze-drying. Optimum freeze-drying condition was investigated based on the relationship between the heating temperature and color change by scorching at the sample surface. The samples were freeze-dried at the constant surface temperatures ranging from 0 to 65°C under the usual pressure range of commercial operations. Thermal conductivities and permeabilities were determined by applying the uniformly-retreating-ice front model to the dried layer of samples undergoing freeze-drying. The surface temperature of 28.8% miso paste was allowed to heat up to 55°C, and its drying rate was limited by the heat transfer rate across the dried layer. Optimum drying condition to produce a cup of freeze-dried miso soup was found to be about 22% in solute concentration and 55°C at surface temperature during drying. Values of thermal conductivity were found to increase with increasing solute concentrations, while no marked effect of the solute concentration was observed on the data of permeabilities, indicating the pressure dependence under our experimental conditions.