29D-3 |
Changes in permeability of moderate electric field (MEF) treated vegetable tissue over time |
S. A. KULSHRESTHA and S. K. Sastry. Dept. of Food, Agricultural & Biological Engineering, Ohio State Univ., 590 Woody Hayes Dr., 260 Agricultural Engineering Bldg., Columbus, OH 43210-1058 Electropermeation of cell membranes of raw plant tissue is potentially useful in drying and juice extraction processes The objective of this study was to examine the structural and low-frequency dielectric spectral response of vegetable tissue subjected to MEF processing for 24 hours after exposure. Raw, thawed, or precooked potato cylinders were chilled, and then warmed to 25ºC by either allowing them to equilibrate or by MEF treatment. The conductivity from 100 Hz to 20 kHz and apparent dielectric constant from 100 Hz to 5 kHz was initially the same between raw, untreated samples and raw, MEF treated samples, but over 24 hours, that of the raw, MEF treated samples increased while that of the raw, untreated samples remained constant. No such distinct pattern emerged from the thawed or precooked samples. The apparent dielectric constant of raw, MEF treated potato above 5 kHz was the same as raw, untreated potato and higher than thawed and precooked potato. None of the samples showed marked changes in dielectric constant at 5-20 kHz over the 24 hour period. Apparently, even mild electrical treatments permeabilize vegetable tissue, permitting enhanced diffusion
Session 29D, Food Engineering: Thermal processes
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