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ARS Home » Southeast Area » Dawson, Georgia » National Peanut Research Laboratory » Research » Publications at this Location » Publication #138689
Title: PERFORMANCE COMPARISON OF RF IMPEDANCE AND DC CONDUCTANCE MEASUREMENTS FOR SINGLE PEANUT KERNEL MOISTURE DETERMINATION

Author
item Kandala, Chari
item Butts, Christopher - Chris

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/30/2006
Publication Date: 1/30/2007
Citation: Kandala, C., Butts, C.L. 2007. PERFORMANCE COMPARISON OF OF IMPEDANCE AND DC CONDUCTANCE MEASUREMENTS FOR SINGLE PEANUT KERNEL MOISTURE DETERMINATION. Transactions of the ASAE. (50)1:171-122.

Interpretive Summary: Peanut is a major crop in the southern part of the United States and a common food item marketed in different forms, such as, boiled peanuts, peanut butter, peanut candy, and peanut oil. Moisture content is an important factor in the harvesting, storing and processing of peanuts. Freshly dug peanuts have much higher moisture contents and are usually left on the vines to dry in windrows. After removal from vines, they are dried with forced air till they reach permissible moisture contents for storage and other purposes. Throughout drying, moisture content is measured at various stages with measuring instruments which measure moisture of bulk peanut kernels. It was found that individual kernels in this bulk sample have a wide range of moisture values different from the average value. These high moisture kernels can develop fungal growth and damage peanuts. Presently, a commercial single kernel moisture meter is available which measures the electrical conductance of a single kernel as it is crushed between two rotating rollers. A parallel-plate system was developed by ARS which measures certain dielectric properties of a single kernel held between two parallel plates without crushing the kernel. Moisture measurements were made using both methods and values were compared to the standard oven method. It was concluded that both methods worked well within certain limits of accuracy, and could be useful tools in processing and storing peanuts.

Technical Abstract: Two methods by which the moisture content of individual kernels of peanuts, Arachis hypogaea L., were compared with a standard forced-air oven method. One method is based on the capacitance, dissipation factor, and/or phase angle measurements of a parallel-plate capacitor with a single peanut held between the plates at two frequencies, 1.0 and 4.5 MHz. The other is a dc conductance measurement on a single peanut as it passed between two crushing-roller electrodes. Moisture content was determined by these two methods and by the standard oven method on 30 individual peanut kernels from 6 lots whose moisture content ranged from 6 to 16%, wet basis. Peanuts used in these measurements were graded into two sizes, jumbo and medium. Both the capacitance and conduction methods came up with moisture content predictions closely in agreement with the standard oven values, irrespective of the size of the kernels. However, the moisture content values obtained by these two methods compared even better with each other than with the standard oven values, particularly at the higher moisture ranges. An advantage of the capacitance method is, it is nondestructive.