Location: Peanut Research
Title: Determination of moisture content using NIR Reflectance Spectroscopty with single calibration for both Valencia and Virginia in-shell peanuts Authors
Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 1, 2012
Publication Date: June 1, 2012
Citation: Kandala, C., Sundaram, J. 2012. Determination of moisture content using NIR Reflectance Spectroscopty with single calibration for both Valencia and Virginia in-shell peanuts. Transactions of the ASABE. 55:2. Interpretive Summary: NIR spectroscopy is well-suited for measurement of MC in grains and nuts, since water O-H group overtone and combination bands are pronounced in this region of the spectrum. Water is a strong absorber in the NIR region, and samples with high water content are strongly dominated by the signature from water. NIR is readily adaptable and the low intensities of NIR absorptions permit the direct measurement of water, over wide concentration ranges, in solid samples. The objectives of this research are to investigate the possibility of predicting moisture contents of in-shell peanuts of both Valencia and Virginia types using the calibration models developed with samples from only one of these two varieties. This is done by: 1. Developing calibration models to predict the moisture content from the reflectance spectra, obtained on in-shell peanut samples of the Virginia type, using NIR reflectance spectroscopy. 2. Predicting the moisture content of both Virginia and Valencia type in-shell peanuts from the developed calibration models of Virginia type, and compare the predicted values with the reference values obtained by the standard air-oven methods. Using NIR reflectance spectroscopy the moisture content of both Virginia and Valencia type in-shell peanuts was determined with a single calibration done on Virginia peanut samples. There are no commercial instruments that would measure the moisture content of peanuts while they are in their shells and the NIR reflectance method would be a good start for developing a commercial instrument. Further, the possibility of predicting moisture content of two types of peanuts with calibration on a single type would be an added advantage for a commercial meter. This method is rapid and nondestructive and could be useful not only in the drying and shelling operations but also in the processing of peanut products.
Technical Abstract: Near infrared (NIR) spectroscopy was used earlier to measure the moisture content (MC) of in-shell peanuts of Virginia and Valencia type. NIR spectral data was collected on calibration sample sets from Virginia type in the moisture range of 6% to 22%, from 400 nm to 2500 nm. Calibration models were developed using the raw data and the derivative data, and an appropriate model, based on certain fitness parameters such as Standard error of calibration and prediction was selected for prediction of MC in validation sets of the Virginia type. Similarly, MC in Valencia type in-shell peanuts were predicted from calibration models developed from Valencia type in-shell peanuts. In this work, calibration models developed using Virginia type in-shell peanuts were used to predict MC in both Virginia and Valencia type validation sets. Ability to predict MC in different types of in-shell peanuts with a calibration model obtained with any single peanut type would save time and labor, otherwise needed in doing multiple calibrations, and could be useful in developing a commercial instrument.