TITLE:
Nondestructive Determination of Moisture Content in Dry Fruits by Impedance and Phase Angle Measurements
AUTHORS:
Chari V. Kandala, Ron Holser, Jaya Sundaram, Naveen Puppala
KEYWORDS:
Cherries, Blueberries, CI Meter, Moisture Content, Capacitance, Impedance, Dry Fruits
JOURNAL NAME:
Journal of Sensor Technology,
Vol.5 No.4,
December
25,
2015
ABSTRACT: An electronic method to estimate the moisture content (MC) of dry fruits by measuring the impedance (Z) and phase angle (θ) of a cylindrical parallel-plate capacitor with dry fruit sample between the plates, using a CI meter (Chari’s Impedance meter) at 1 and 9 MHz is described. Capacitance C was derived from Z and θ, and using the C, θ, and Z values of a set of dried cherries, whose MC values were later determined by the vacuum hot air-oven method, a calibration equation was developed. Using this equation, and their measured C, θ, and Z values, the MC of a group of cherries, not used in the calibration, was predicted. The predicted values were compared with their air-oven values. Similar predictions were done using the same method on dried blueberries. The method worked well with a good R2 value, and showed a low standard error of prediction (SEP) in the measured MC range between 5% and 30% for cherries, and 9% and 22% for blueberries.