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THE EFFECT OF FREQUENCY AND WAVE FORM ON THE ELECTRICAL CONDUCTIVITY‐TEMPERATURE PROFILES OF TURNIP TISSUE 1
Author(s) -
LIMA MARYBETH,
HESKITT BRIAN F.,
SASTRY SUDHIR K.
Publication year - 1999
Publication title -
journal of food process engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 45
eISSN - 1745-4530
pISSN - 0145-8876
DOI - 10.1111/j.1745-4530.1999.tb00470.x
Subject(s) - electrical resistivity and conductivity , conductivity , materials science , chemistry , physics , quantum mechanics
ABSTRACT Electrical conductivity (σ) – temperature (T) curves were determined as a function of frequency and wave form of alternating current. Turnip cylinders were sandwiched between titanium electrodes and heated ohmically to 100C using four frequencies (4, 10, 25 and 60 Hz) and three wave forms (square, sine and sawtooth). The σ‐T curve shifted upward at 4 Hz for all wave forms. Curses were not significantly different at 10, 25 and 60 Hz for sawtooth and sine wave forms, while those for square waves were not significantly different at any of the frequencies tested. A comparison of wave forms showed that σ‐T curves for square waves were shifted downward significantly with respect to sine and sawtooth waves. Heating rate increased with decreasing frequency. Changes in vegetable tissue cellular structure are believed to be responsible for these results. Further research is necessary to characterize these mechanisms.