Dmytrenko N. Water conditions influence on the thermal properties and the drying process of plant raw material

The dissertation devoted to the experimental impact of water conditions in native and heat-treated plant tissues of different chemical composition on the heat of vaporization, heat capacity of plant tissues and kinetics of tissues drying. Potato, apple and willow shoots tissue were investigated on the devices and with methods of differential calorimetry. Has been analyzes the influence of the chemical composition of tissues on the process of binding water. It has been found that the specific content of bound water, the consumption of heat for evaporation and their changes are determined by hydration ability of components of plant tissues and its changes during the previous heat treatment and drying. Has been first registered influence of moisture content on evaporation heat of water from plant tissue. The results showed that long before removing hygroscopic moisture heat of evaporation of water from plant tissues may exceed the heat of vaporization of pure water. For moment before removing hygroscopic moisture total expenditure of heat for evaporation exceed the costs of vaporization of pure water at 6% for heat-treated tissues potatoes, 5.6% for tissues apple and 1% for willow shoots. Has been received the analytical dependences of the specific heat of moist tissues of apple, potato and willow shoots on the temperature and humidity. Has been proven the violation of the rules of additivity for the specific heat of moist plant tissues. The glass transition of plant tissues and powders with low moisture content were fixed at positive temperatures. Temperature shift of the formation of starch gel was detected with decreasing moisture content of the potato tissue. Both effects influence the production technology. It was determined that the changes drying kinetics correspond change the dynamic state of water in the tissues and the energy of tissue dehydration. Mechanism and the removal sequence of water from the plant tissues during drying have been updated. Thermal drying efficiency plant tissue has been assessed.