Submitted to: Pacific Division American Association for the Advancement of Science
Publication Type: Abstract Only
Publication Acceptance Date: 1/4/2006
Publication Date: 2/16/2006
Citation: Nelson, S.O., Trabelsi, S., Kays, S.J. 2006. Dielectric spectroscopy of honeydew melons [Abstract] [CD-ROM]. Annual Meeting Abstracts of the American Association for the Advancement of Science, p. A146.
Technical Abstract: Techniques for nondestructive determination of quality of agricultural products are helpful to producers, handlers, processors, marketers and consumers. Visible and physical characteristics of many fresh fruits, such as color, size, weight, density, elasticity, and firmness can be used for automatic sorting into different categories for the market. For the honeydew melon, however, no useful characteristics of this type have been found for reliable correlation with maturity and sweetness. The criterion for maturity in fruit is the measurement of soluble solids, which are mostly sugars, and therefore a measure of sweetness. This requires the extraction of tissue samples from the melons and measurement of expressed juice with a refractometer that has been calibrated to indicate percentage of soluble solids. Honeydew melons were grown and harvested with a range of maturities for measurement of tissue dielectric constant and loss factor by dielectric spectroscopy to study correlations between the dielectric properties and soluble solids content for nondestructive sensing of quality. These properties of tissue samples from 38 melons were measured at 25 'C over the frequency range from 10 MHz to 1.8 GHz along with refractometer determinations of soluble solids content (SSC), and tissue density and moisture content. A high correlation (r = 0.96) was found between SSC and the permittivity as expressed in a complex-plane plot of the dielectric constant and loss factor, each divided by SSC. Through this mathematical relationship, SSC can be calculated from measured permittivity values independent of tissue density, moisture content, and most likely independent of temperature as well.