NONDESTRUCTIVE MOISTURE CONTENT DETERMINATION OF IN-SHELL PEANUTS BY RF IMPEDANCE METHOD

摘要

Measuring the moisture content of peanuts without shelling the peanuts, particularly during buying/selling and drying, would be beneficial to the peanut industry. Previous research has shown that radio frequency (RF) impedance measurements of capacitance (C) and phase angle (0) using a parallel-plate system could be used to estimate the moisture content (MC) of a single in-shell peanut. This method was extended to determine the average MC of a small sample of peanut pods accommodated between the plates. For both single pods and small samples, the predicted MC values were within 1% of the standard air-oven values for over 85% of the samples tested in the moisture range between 5% and 22%. The current research discusses extending the measurement system to predict the average MC of in-shell peanuts in bulk quantities (about 200 g) from similar capacitance and phase angle measurements at 1 and 9 MHz. The parallel-plate system used in previous research was modified and fitted into a non-conducting cylindrical sample holder.