ARS | Publication request: Near-infrared (NIR) prediction of trans-fatty acids in ground cereal foods

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 14, 2008
Publication Date: September 21, 2009
Repository URL: http://hdl.handle.net/10113/37884
Citation: Kim, Y., Kays, S.E. 2009. Near-infrared (NIR) prediction of trans-fatty acids in ground cereal foods. Journal of Agricultural and Food Chemistry. vol. 57, pp. 8187-8193, 2009.

Interpretive Summary: Trans fats are present in foods predominantly as fat or oil ingredients that have been processed by partial hydrogenation to give improved properties for food processing. Because of adverse effects on health trans fat are included in the U.S. Nutrition Labeling and Education Act (Code of Federal Regulations, 2006) and the amount of trans-fat in a product must be declared on the nutrition label if more than 0.5 g is present per serving. Conventional methods of evaluation of trans fats, although accurate and repeatable, are laborious, time consuming and use large volumes of organic solvents, which are hazardous, flammable and require specific disposal. Spectroscopic methods of evaluation are rapid, require minimal labor once a mathematical model has been develop and do not require the use of chemicals or create chemical waste. Near infrared (NIR) reflectance spectroscopy, which measures the amount of light energy reflected by a substance, represents a very rapid and accurate method of measuring constituents of materials without requiring extensive sample preparation, nor creating chemical pollutants. This study was conducted to evaluate the feasibility of NIR spectroscopy for evaluation of trans- fatty acids in ground cereal products without the need for oil extraction. Models were developed using chemometric techniques based on different wavelengths and based on correlations between parameters. It was found that NIR spectroscopy is a suitable method for screening ground cereal products for trans-fatty acid content. NIR spectroscopy may also be suitable for evaluation of cis-fatty acids for subsequent evaluation of trans by calculation.

Technical Abstract: Near infrared (NIR) reflectance spectroscopy was evaluated as a rapid method for prediction of trans-fatty acid content in ground cereal products without the need for oil extraction. NIR spectra (400-2498 nm) of ground cereal products were obtained with a dispersive NIR spectrometer and correlated to trans- and cis-fatty acid content determined by a modified AOAC Method 996.01. Partial least squares regression and Marten’s uncertainty test were applied to calculate models for prediction of trans-fatty acids using spectral regions affected by lipid absorption. The best model (n=84) for trans-fat prediction used the 700-2498 nm region and second derivative processing of spectra. The model had an RPD of 4.8 when used to predict test samples (n=27) with standard error of performance of 0.70 (range 0.05-11.74) % and r2 of 0.97. Optimum models for cis-fatty acids were developed with the 1100-2498 and 700-2498 nm ranges and had an RPD of 4.0. Regression coefficients indicated that useful absorbance for prediction of trans- and cis-fatty acids was in the overtone and combination regions for lipid absorption.