Radio-Frequency Dielectric Properties of Some Tropical African Leaf Vegetables

摘要

The variation of the relative permittivity epsilon'sub(r), the loss factor epsilon'' and a.c. conductivity sigma with the frequency of an applied electromagnetic field over the range 0.5 to 50 MHz has been studied in the leaf and stem tissues of three tropical vegetables viz, amaranthus, better leaf and okra. This is with a view to investigate the molecular structure and dielectric heating characteristics of the leaves and stems in the different vegetables considered. The Cole-Cole plots of the data showed that in all cases, both the stems and leaves exhibited a spread of relaxation times, indicating heterogeneity of structure. In general, the a.c. conductivity and the dielectric energy loss factor also appear to be much larger in the vegetable stems than in the leaves, suggesting that energy dissipation in stems is greater than in the leaves. (ERA citation 12:014392)