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ARS Home » Southeast Area » Dawson, Georgia » National Peanut Research Laboratory » Research » Publications at this Location » Publication #310625

Research Project: Systems to Assess, Monitor, and Preserve Peanut Quality and Safety

Location: National Peanut Research Laboratory

Title: Analysis of Total Oil and Fatty Acids Composition by Near Infrared Reflectance Spectroscopy in Edible Nuts

item Kandala, Chari
item Sundaram, Jaya - University Of Georgia

Submitted to: Proceedings of SPIE
Publication Type: Proceedings
Publication Acceptance Date: 6/20/2014
Publication Date: 8/21/2014
Citation: Kandala, C., Sundaram, J. 2014. Analysis of Total Oil and Fatty Acids Composition by Near Infrared Reflectance Spectroscopy in Edible Nuts. Proceedings of SPIE.

Interpretive Summary: Summary Moisture content (MC) and oil are important grading factors in the sale and purchase of edible nuts, particularly peanuts (Arachis hypogaea L.). Accurate measurement of peanut moisture content is critical in marketing, storing, and processing. NIR reflectance spectroscopy could be a useful tool for the analysis of moisture, total oil and fatty acids content of in-shell peanuts with minimal sample preparation. NIR measurement is procedurally very simple, considerably reducing the time required for composition measurements compared to standard analytical procedures. RPD values of Virginia type in- shell peanuts showed that the calibration models developed using both reflection and absorption derivative data were good enough for the prediction of moisture content and total oil percentage. For Valencia in-shell peanuts all the parameters, such as total oil, oleic, linolenic and stearic acids gave safe RPD values, above 3. With further improvement in the analysis of NIR data it will be possible to predict the fatty acid composition with sufficient accuracy for quality control purposes.

Technical Abstract: Near Infrared (NIR) Reflectance spectroscopy has established itself as an important tool in quantifying water and oil present in various food materials. It is rapid and nondestructive, easier to use, and does not require processing the samples with corrosive chemicals that would render them non-edible. Earlier, the samples had to be ground into powder form before making any measurements. With the development of new soft ware packages, NIR techniques could now be used in the analysis of intact grain and nuts. While most of the commercial instruments presently available work well with small grain size materials such as wheat and corn, the method present here is suitable for large kernel size products such as shelled or in-shell peanuts. Absorbance spectra were collected from 400 nm to 2500 nm using a NIR instrument. Average values of total oil contents (TOC) of peanut samples were determined by standard extraction methods, and fatty acids were determined using gas chromatography. Partial least square (PLS) analysis was performed on the calibration set of absorption spectra, and models were developed for prediction of total oil and fatty acids. The best model was selected based on the coefficient of determination (R2), Standard error of prediction (SEP) and residual percent deviation (RPD) values. Peanut samples analyzed showed RPD values greater than 5.0 for both absorbance and reflectance models and thus could be used for quality control and analysis. Ability to rapidly and nondestructively measure the TOC, and analyze the fatty acid composition, will be immensely useful in peanut varietal improvement as well as in the grading process of grain and nuts.