MICROWAVE SENSING TECHNIQUE FOR NONDESTRUCTIVE DETERMINATION OF BULK DENSITY AND MOISTURE CONTENT IN UNSHELLED AND SHELLED PEANUTS

摘要

A microwave dielectric method was used to determine nondestructively and simultaneously bulk density and moisture content in unshelled and shelled peanuts from measurement of their relative complex permittivities in free space at 8.0 GHz and 24℃. Bulk density was determined without requiring knowledge of moisture content and temperature of unshelled and shelled peanut samples from a complex-plane representation of the relative complex permittivity. Moisture content in unshelled and shelled peanuts was determined independent of bulk density with the use of a density-independent permittivity calibration function. Statistical analysis provided bulk density and moisture content calibration equations along with corresponding standard errors of calibration and standard errors of performance over wide ranges of bulk density and moisture content. In addition, an equation was established for determining moisture content in peanut kernels directly from measurements of microwave dielectric properties of unshelled peanuts.