JST  Vol.5 No.4 , December 2015
Nondestructive Determination of Moisture Content in Dry Fruits by Impedance and Phase Angle Measurements
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.
Cite this paper: Kandala, C. , Holser, R. , Sundaram, J. and Puppala, N. (2015) Nondestructive Determination of Moisture Content in Dry Fruits by Impedance and Phase Angle Measurements. Journal of Sensor Technology, 5, 73-80. doi: 10.4236/jst.2015.54008.

[1]   Brothwell, D. and Brothwell, P. (1998) Food in Antiquity: A Survey of the Diet of Early People. John Hopkins University Press, Baltimore and London, 144-147.

[2]   Hui, YH. (2006) Handbook of Fruits and Fruit Processing. Blackwell Publishing, Oxford, 81.

[3]   AOAC (1990) Official Method of Analysis of the Association of Official Analytical Chemists. No. 934.06, AOAC, Arlington.

[4]   Windham, W.R. (1989) Comparison between Liquid and Paste Karl Fischer Extraction for NIRS Water Calibrations. Journal of the Association of Official Analytical Chemists, 72, 255-258.

[5]   Kandala, C.V.K. and Nelson, S.O. (1990) Measurement of Moisture Content in Single Kernels of Peanuts: A Nondestructive Electrical Method. Transactions of the ASAE, 33, 567-572.

[6]   Kandala, C.V.K., Avula, R., Settaluri, V., Reddy, R.S. and Puppala, N. (2013) Sensing the Moisture Content of Dry Cherries—A Rapid and Nondestructive Method. Food and Nutrition Sciences, 4, 38-42.

[7]   Kandala, C.V.K. and Sundaram, J. (2010) Nondestructive Measurement of Moisture Content Using a Parallel-Plate Capacitance Sensor for Grain and Nuts. IEEE Sensors Journal, 10, 1282-1287.

[8]   Kandala, C.V.K., Butts, C.L. and Lamb, M.C. (2008) Moisture Content Determination for In-Shell Peanuts With a Low-Cost Impedance Analyzer and Capacitance Sensor. Transactions of the ASAE, 51, 1377-1381.

[9]   Unscrambler, Version 9.7. CAMO Software Inc., Woodbridge.

[10]   SAS Institute (2000) Statistical Analysis Software for Windows, Version 8.1, SAS Institute, Cary.