Abstract
Impedance spectra in the range from 10 Hz to 1 MHz were obtained for apples for temperatures between 4 and 40 °C. At each temperature the measured spectrum was fitted to a theoretical model in which the bulk properties of the apple were represented as the parallel combination of a constant phase element and a resistance. The results were used to determine the activation enthalpies of apples for ionic migration, Hm, and for dissociation of an ion from its binding site, Hf. Hm was found to be of the order of 0.15 eV whereas Hf was of the order of 0.03 eV. Changes in the slope of the activation curves indicated that a structural change occurred in the cell wall within the temperature range between 35 °C and 40 °C.
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Hart, F.X., Schmidt, V., Ray, L. et al. Measurement of the activation enthalpies of ionic conduction in apples. Journal of Materials Science 33, 3919–3925 (1998). https://doi.org/10.1023/A:1004684310108
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DOI: https://doi.org/10.1023/A:1004684310108