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United States Department of Agriculture

Agricultural Research Service

Research Project: POST HARVEST MEASUREMENT AND MANAGEMENT SYSTEMS TO IMPROVE PEANUT QUALITY AND US COMPETITIVENESS

Location: Peanut Research

Title: NIR reflectance method to determine the Moisture Content in Peanuts

Authors
item KANDALA, CHARI
item Govindarajan, K - UNIVERSITY OF NEBRASKA
item Subbiah, Jeyam - UNIVERSITY OF NEBRASKA

Submitted to: Proceedings of SPIE
Publication Type: Proceedings
Publication Acceptance Date: January 15, 2008
Publication Date: August 6, 2008
Citation: Kandala, C., Govindarajan, K.N., Subbiah, J. 2008. NIR reflectance method to determine the Moisture Content in Peanuts. Proceedings of SPIE. San Diego, CA.

Interpretive Summary: Moisture content (mc) in peanuts is an important property that is measured and monitored at various stages of their processing and storage in the peanut industry. In this work an NIR (Near Infrared Radiation) reflectance method, that would rapidly determine the average mc of a peanut sample (about 100 g of shelled peanuts), is described. Presently available commercial meters that use NIR methods do require some sort of a sample preparation such as grinding the samples to certain size and filling them in containers of certain volume. This is time consuming. In the present method, reflectance spectra of 30 samples of peanut kernels (shelled peanuts) from each of nine different moisture levels, with known mc values (as determined by the standard air-oven method) in the moisture range of 6 to 20 %, was collected using a NIR spectrometer in the wave length range of 1000-1800 nm. A calibration model was developed by using partial least squares regression procedures. Using this model the mc of a number of peanut samples at seven different moisture levels in the same moisture range, but that were not used in the calibration, was predicted. The predicted values were compared with their air-oven values, determined by the standard method. The predicted mc values of the 180 samples tested in the above moisture range compared well with their air-oven values with an r2 value of 0.99 and a root mean square error of 1.15. The standard error of prediction was 0.81. The NIR reflectance method may be useful for the rapid determination of mc in shelled peanuts with out the need for any grinding or other types of sample preparation. This being a non-contact method would be particularly suitable for measurement of mc of edible materials such as grain and other types of nuts, as they move on conveyor belts during processing.

Technical Abstract: Moisture content (mc) in peanuts is an important property that is measured and monitored at various stages of their processing and storage in the peanut industry. In this work an NIR (Near Infrared Radiation) reflectance method, that would rapidly determine the average mc of a peanut sample (about 100 g of shelled peanuts), is described. In this method, reflectance spectra of several samples of peanuts, with known mc values (as determined by the standard air-oven method) in the moisture range of 6 to 20 %, was collected using a NIR spectrometer in the wave length range of 1000-1800 nm. A calibration model was developed by using partial least squares regression procedures. Using this model the mc of a number of peanut samples in the same moisture range, but that were not used in the calibration, was predicted. The predicted values were compared with their air-oven values, determined by the standard method. The predicted mc values of the 180 samples tested in the above moisture range compared well with their air-oven values with an r2 value of 0.99 and a root mean square error of 1.15. The standard error of prediction was 0.81. The NIR reflectance method may be useful for the rapid determination of mc in shelled peanuts with out the need for any grinding or other types of sample preparation.

Last Modified: 8/19/2014
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