Rapid Chemometric Method for the Determination of Oleic and Linoleic Acid in Sunflower Seeds by ATR-FTIR Spectroscopy

Abstract

Screening of sunflower seeds in a breeding program to produce high oleic acid varieties requires a fast, simple and accurate analytical method. Experiments were carried out to: (i) investigate the potential of attenuated total reflectance-fourier transform infrared (ATR-FTIR) spectroscopy for rapid determination of fatty acid in sunflower seeds; and (ii) evaluate the calibration models for determination of oleic and linoleic acid contents in sunflower seeds by ATR-FTIR. Spectral data manipulation was performed using 5 different processing treatments for monitoring the calibration models, including two pretreatments (1st and 2nd derivative), two preprocessing strategies (Multiplicative Scatter Correction (MSC), vector and min/max normalization), and spectral ranges (3050-2800 and 1800-900 cm–1). FTIR spectra combined with gas chromatography (GC) values of oleic and linoleic acid contents were used for predictive models generated by partial least square (PLS) regression. The results showed that treatments 1 and 2, the combinations of 2nd derivative with MSC or vector normalization in spectral ranges 3050-2800 and 1800-900 cm-1, presented the lowest errors and produced the highest coefficients of determination of oleic and linoleic acid prediction models. It can be concluded that the ATR-FTIR method combined with chemometric analysis provided results comparable to GC analysis but they are more rapid and simple.