Agricultural Applications of Dielectric Spectroscopy

A brief account of interest in dielectric properties of agricultural materials is presented, and some examples of dielectric spectroscopy applied to agricultural problems are discussed. Included are wide frequency range (250 Hz to 12 GHz) permittivity, or dielectric properties, measurements on adult rice weevils and hard red winter wheat, for the purpose of assessing selective dielectric heating of the insects, and broadband (200 MHz to 20 GHz) permittivity measurements on tissues of fresh fruits and vegetables. Similar measurements are shown for tree-ripened peaches, which were obtained to assess possibilities for a permittivity-based maturity index. Broadband (10 MHz to 1.8 GHz) permittivity measurements are shown for several fruits and vegetables as a function of temperature from 5 to 95 degrees C. Measurements over the same frequency range and similar temperature ranges are presented for two other food products, whey protein gel and apple juice. A few comments are offered on likely future dielectric spectroscopy applications in agriculture.