Attenuated Total Reflectance–Fourier Transform Infrared (ATR–FTIR) Spectroscopy Combined with Chemometrics for Rapid Determination of Cold-Pressed Wheat Germ Oil Adulteration
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This paper describes the feasibility of attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectroscopy combined with multivariate data analyses for rapid determination of cold-pressed wheat germ oil (WGO) adulteration. Thirty-six pure edible oils, as well as 216 binary blends of WGO adulterated with cheaper refined oils, sunflower (SFO), and soybean oil (SBO) (1–50%) were analyzed by using ATR–FTIR spectroscopy in combination with PCA, LDA, SIMCA, and PLSR analyses. SIMCA models provide excellent classification for pure cold-pressed WGO and refined edible oil samples, with 95% significance level. The classification limits for detection of SFO and SBO adulterations in WGO were below 1%. Furthermore, a total of 100% of studied samples were correctly classified on the basis of their origin in calibration and in cross-validation by LDA models. Under the optimum conditions, the PLS–R plots of actual versus predicted values exhibited high linearity (R2 > 0.9990). The content of SFO and SBO adulterants has been successively quantified using PLSR at levels < 0.56% and < 0.99% in an unknown mixture. RMSEC and RMSECV values for the binary mixtures of WGO–SFO were between 0.56–1.98% and 0.68–4.46%, for the binary mixtures of WGO–SBO were between 0.99–1.77% and 1.09–5.12%, respectively.
KeywordsAdulteration Wheat germ oil Spectroscopy Chemometrics
Attenuated total reflectance
Cotton seed oil
Fatty acid methyl ester
Flame ionization detector
Fourier transform infrared
Principal component analysis
Partial least squares regression
Root mean square error of calibration
Root mean square error of cross validation
Soft independent modeling of class analogies
Wheat germ oil
Linear discriminant analysis
Polyunsaturated fatty acids
Monounsaturated fatty acids
Saturated fatty acids
Standard normal variate
The present study is a part of the master thesis entitled “Development of chromatographic and molecular spectroscopic multivariate chemometric models for the determination of cold pressed wheat germ oil adulteration with refined vegetable oils.” This study is supported financially by the Scientific Research Project Center of Karamanoglu Mehmetbey University (Project number 18-M-17). The authors would also like to thank TUBITAK under the 2219–Research Fellowship Program for International Postdoctoral for providing the financial support to carry out this research work.
Compliance with Ethical Standards
Conflict of Interest
Fatma Nur Arslan declares that she has no conflict of interest. Fethi Çağlar declares that he has no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
Informed consent was obtained from all individual participants included in the study.
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