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United States Department of Agriculture

Agricultural Research Service

Title: Predicting Protein Content by Near Infrared Reflectance Spectroscopy in Diverse Cereal Food Products

Authors
item Kays, Sandra
item Barton Ii, Franklin
item Windham, William

Submitted to: Near Infrared Spectroscopy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 5, 1999
Publication Date: N/A

Interpretive Summary: Near- infrared(NIR) spectroscopy represents a rapid and accurate method of measuring constituents of materials without requiring extensive sample preparation, nor creating chemical waste. A considerable advantage of NIR spectroscopy as an analytical technique is the ability to quantitatively determine several constituents of a product simultaneously. Previous work has demonstrated that NIR reflectance spectroscopy can be used to predict total dietary fiber content, rapidly and accurately, in a wide range of cereal products. The present study demonstrates that NIRS can be also be used to predict protein content in a wide range of cereal products. Simultaneous determination of total dietary fiber and protein content would be highly advantageous in the monitoring of these nutrients for compliance with the U.S. Nutrition Labeling and Education Act and has utility for the cereal product industry and commercial analysis laboratories.

Technical Abstract: An advantage of near-infrared (NIR) spectroscopy as an analytical technique is the ability to quantitatively determine several constituents of a product simultaneously. Previous work has described the development of NIR reflectance models for the prediction of dietary fiber in a diverse group of cereal food products. The present study was conducted to investigate NIR spectroscopy as a method of evaluating protein content in a similar group of cereal products. Nitrogen and crude protein contents of dry- milled products (n=148) were measured by the combustion analysis method (AACC Method 46-30/ AOAC Method 992.23). The range in nitrogen values was from 0.65 to 3.31% of dry weight. Milled cereal products were scanned from 1100- 2500 nm with an NIRSystems 6500 monochromator. Using a commercial analysis program for scanning and data analysis, a nitrogen calibration was obtained with partial least squares as the regression method. The standard derror of cross validation and multiple coefficient of determination were 0.090% and 0.973, respectively. The calibration was validated using a set of independent cereal products (n=74). The validation samples were predicted with a standard error of performance of 0.079% nitrogen and coefficient of determination of 0.984. Protein was calculated using several nitrogen-to-protein conversion factors and calibrations developed for the prediction of protein. The results show NIR spectroscopy can be used to rapidly and accurately predict nitrogen and subsequently crude protein content, in a diverse range of cereal products, simultaneously with dietary fiber.

Last Modified: 10/20/2014
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