| With the development of science technology, many advanced electromagnetic processing technologies have been developed. One of the most popular research areas is using ohmic heating technology to heat foodstuff and measure physical properties parameters and another is electrostatic drying because the electrostatic field can promote the evaporating and drying procedure. But there are some other electromagnetic technologies have not got systemic research such as the electrical conductivity of foodstuff, how to use the electric conductivity to measure starch gelatinization temperature and the foodstuff drying process under high voltage electrostatics field, including the energy consume and the energy efficient ratio. For the better application of these technologies, the further research should focus on the electric conductivity including its temperature variability and foodstuff drying theory and energy economy under high voltage electrostatics field.Based on theories of Physics, Electromagnetics, Food physics, Chemical Engineering, Electrostatics and Measurement technology, there are two parts addressed in the thesis: One is the research of electric conductivity variation in soybean milk and starch suspension heating process, with the development of electric conductivity measurement system. The other is the design of high voltage electrostatics field experimental device, under which the destilled water evaporation and foodstuff drying process were studied. The main results are as follows:1. Designed and manufactured a minitype ohmic heating device, named OH-4A, for research. The heating rate can be controlled with different control program.2. The relationship between the electrical conductivity of the different solids content soybean milk heated in water bath and its temperature has been researched with an electrical conductometer. The results show that the heating rate does not affect the electrical conductivity of the soybean milk. When the soybean milk with constant solids content was heated by ohmic heating principle with sinusoidal alternating current, which frequency is 50 Hz and the voltage is constant, there are no effects of the voltage value on the electrical conductivity of soybean milk, and the change of the electrical conductivity with the temperature is similar to the change of the electrical conductivity measured with the electrical conductometer when heated in water bath. When the soybean milk was ohmically heated with OH-4A minitype device at a constant heating rate, which control component is the solid state relay (SSR), the electrical conductivity was not only a function of the solids content but also the heating rate. The main reason of this phenomena is that the ship of the voltage wave was changed by SSR.3. From ohmic heating experiments in same voltage with different species of starch suspension in variation concentration, the law of the electrical conductivity variation following temperature was developed. The mechanism of the electrical conductivity decreases in gelatinization temperature range is anlysized. The do/dT-T curve is similar as the heat absorption peak shape which is measured by DSC, so the starch gelatinization temperature can be determined in do/dT-T curve following the DSC heatabsorption peak curve. And in this research, the da/dT-T curve, which is similar as DSC curve, was defined as "block peak" firstly for the electrcial conductivity decreases when the starch grain expands to reduce the electrical particle passing area. The experiment results show that there is no block peak on the da/dT-T curve of the pregelatinization starches.4. The higher the concentration of the starch suspension, the more evident of the block peak shape in da/dT-T curve and the larger area of the block peak among the line of d a /dr=constant and d a /dT, certainly it is in favor of the measurement of the gelatinization temperature. When the mass ratio of starch to water is a constant, the block peak's shape is more evident with the salt content increase because of the incre...
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