Application of Alternative Current Impedance Spectroscopy Analysis on the Analyzing Electrical Properties for Solid Foods
碩士 === 國立海洋大學 === 食品科學系 === 91 === The study used alternative current (AC) impedance spectroscopy analysis and direct conductivity measuring device to measure dielectric constant, dielectric loss and electric conductivity of solid foods. Electrical properties in the frequency range of 10~...
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| Format: | Others |
| Language: | zh-TW |
| Published: |
2002
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| Online Access: | http://ndltd.ncl.edu.tw/handle/78624708853989789538 |
| Summary: | 碩士 === 國立海洋大學 === 食品科學系 === 91 === The study used alternative current (AC) impedance spectroscopy analysis and direct conductivity measuring device to measure dielectric constant, dielectric loss and electric conductivity of solid foods. Electrical properties in the frequency range of 10~100kHz was analyzed. Problems concerning electrode-solid sample contact were eliminated by applying an adequate pressure (0.2kg/cm2). The equivalent circuit of foods obtained by AC impedance spectroscopy analysis could describe foods’ impedance property at various frequencies. Effects of resistor and capacitor of foods were analyzed to realize the ionic conductivity. Foods conductivity was also affected by the orientation of vascular tissue or muscular fiber in AC electric fields. Higher conductivity was obtained when vascular tissue or muscular fiber was parallel to electric fields. The electric conductivity of vegetables and fruits decreased with decreasing frequency at the frequency range 10k~100kHz when charge transferred mainly by dielectric induction. Dielectric constant and dielectric loss increased slightly in the mean time. At about 10kHz bound water started to resulted in increased dielectric loss of all vegetables and fruits. Ionic conduction predominated and the conductivity was independent on the frequency. Dielectric constant remained uncharged at these frequencies. At frequencies below 100Hz, ions and charged molecules underwent space charge polarization and ionic conductivity decreased while dielectric loss of vegetables and fruits increased sharply. Ionic conduction of persisted even at the highest frequency (100kHz) for meats. Space charge polarization occurred at frequencies below 1kHz. Fatty constituents in meats would increase relaxation time and thus decrease electric conductivity.
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