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ARS Home » Southeast Area » Dawson, Georgia » National Peanut Research Laboratory » Research » Publications at this Location » Publication #273547

Title: Capacitance sensors for the nondestructive measurement of moisture content in in-shell peanuts

item Kandala, Chari
item Butts, Christopher - Chris

Submitted to: Proceedings of SPIE
Publication Type: Proceedings
Publication Acceptance Date: 5/20/2011
Publication Date: 6/1/2011
Citation: Kandala, C., Butts, C.L. 2011. Capacitance Sensors for the nondestructive measurement of Moisture Content in in-shell Peanuts. Proceedings of SPIE. 6531-34.

Interpretive Summary: none required.

Technical Abstract: Moisture content (mc) in peanuts is measured at various stages of their processing and storage in the peanut industry. An instrument was developed earlier that would measure the capacitance and phase angle of a small sample of peanuts held between two circular parallel-plates at two frequencies 1 and 5 MHz. These values were used in an empirical equation, developed using the capacitance and phase angle values of samples of known mc levels, to obtain the average mc values of peanut samples with moisture values in the range of 7 to 18%. In the present work, two rectangular parallel-plates were mounted inside a vertical cylinder made of acrylic material and filled with about 200 g of in-shell peanuts and their average mc was determined from a similar empirical equation. The calculated mc values were compared with those obtained by the standard air-oven method. For over 85% of the samples tested in the moisture range between 8 and 17% the mc values were found to be within 1% of the air-oven values. Ability to determine the mc of in-shell peanuts without shelling and cleaning them, as is done presently, will save time, labor and sampling material for the peanut industry.