ASSESSMENT OF MICROWAVE PERMITTIVITY FOR SENSING PEACH MATURITY

Permittivity measurements were taken from 0.2 to 20 GHz on fresh peaches of three varieties at three stages of maturity during the harvest season to determine whether dielectric properties might be correlated with maturity. Other physical properties of the peach tissue, such as density, moisture content, firmness, and total soluble solids content, were also determined. Several indices, based mainly on dielectric constant and loss factor values at 0.2 and 10 GHz, were developed that are related to stage of maturity, but their values were dependent on the variety. Correlations of the permittivity-based maturity indices with tissue firmness and other properties are presented. Further studies, including permittivity measurements at frequencies lower than 0.2 GHz, are needed to determine the practical usefulness of such permittivity-based maturity indices.