Scope and method of study. The application of non-destructive pecan quality assessment is important to both pecan growers and pecan buyers and would allow quick, easy, and reliable quality checks of pecan batches before transactions occur. This research analyzed pecan samples using electromagnetic waves in the radio/microwave range from 100 MHz to 2.5 GHz with an open air transmission-type measurement device. Fifteen to 20 new-crop samples each of the Maramec, Kanza, Pawnee, and Giles cultivars ranging from 20 to 28 nuts per sample depending on the size of the cultivar were analyzed for the signal attenuation and phase shift caused by the sample of pecans using a network analyzer. Samples of each cultivar varied in both overall quality and moisture content. Physical quality parameters of each sample were also measured, such as in-shell density, edible kernel mass, non-edible kernel mass, volume percent fill, packing material mass, shell mass, kernel water content, and shell water content. Each measure of quality was correlated with the signal attenuation and phase shift caused by the sample at each of the 101 measured frequencies, with the best matches reported.

Findings and conclusions. Results suggest there is a linear correlation between both total kernel mass and edible kernel mass with both signal attenuation and phase shift measurements in the 400 to 500 MHz and 1.00 to 1.10 GHz ranges, while there is very little correlation between shell mass and signal attenuation and phase shift at any frequency. At these same frequencies the mass of water in the kernel can be correlated with both signal attenuation and phase shift measurements. Results can be applied to design a non-destructive and automatic pecan grading machine to further the market technologically.