Factors influencing the fatty acid determination in fats and oils using Fourier transform near‐infrared spectroscopy

Abstract

AbstractFourier transform near‐infrared (FT‐NIR) technology is matrix dependent and thus highly dependent on factors that influence the absorption spectra. Ignoring these factors during the development of FT‐NIR models will affect the accuracy and reliability of the classification of fats and oils and the determination of their fatty acid (FA) composition. Four factors were studied: the temperature at which samples are scanned, differences in FA chain length and number of double bonds, and the presence of non‐triacylglycerol components. The results showed that an increase in the recording temperature decreased the absorption peak intensity, but not the position. FT‐NIR spectral differences were linked to variations in molecular vibrations resulting from the number of carbon atoms or double bonds in the FA. The FT‐NIR method could clearly differentiate between chain lengths from 10:0 to 18:0 and numbers of double bonds from zero (18:0) to three (18:3). Contaminants in triacylglycerols altered the FT‐NIR spectra, resulting in increased errors in the FA content. An increased concentration of β‐sitosterol in triolein decreased or increased the observed contents of cis9‐18:1 and cis11‐18:1, respectively. An FT‐NIR model adjusted for the phytosterol content corrected this discrepancy. The revised FT‐NIR model was successfully used to provide the accurate FA compositions of commercial sunflower oils.