The Use of Raman Spectroscopy and Methods of Quantum Chemistry for Assessing the Relative Concentration of Triglycerides of Oleic and Linoleic Acids in a Mixture of Olive Oil and Sunflower Seed Oil


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Abstract

The Raman spectra of five samples of sunflower seed oil and five samples of cold-pressed olive oil of various brands are recorded in the range of 500–2000 cm–1. Within the framework of the B3LYP/6-31G(d)/6-31G(d,p)/6-31+G(d,p)/6-311G(d)/6-311G(d, p)/6-311+G(d,p) methods, the structural models of eight fatty acids (oleic, linoleic, palmitic, stearic, α-linolenic, arachidonic, eicosapentaenoic, and docosahexaenoic) are constructed, and also within the framework of the B3LYP/6-31G(d) method, the structural models of triglycerides of the first four of the above acids are obtained. The vibrational wavenumbers and intensities in the IR and Raman spectra are calculated. The Raman spectra of olive oil and sunflower seed oil were simulated by using the supermolecular approach. We investigated the dependence of the relative intensity of the vibrational bands νexp = 1660 and 1445 cm–1 on the concentration of triglycerides in oils of oleic and linoleic acids and the dependence of the intensity of these bands on the degree of saturation of fatty acids. Experimental and empirical dependences are constructed to estimate the relative concentration of triglycerides of oleic and linoleic acids in a mixture of olive oil and sunflower seed oil. The applicability of the density functional theory together with the vibrational spectroscopy for the identification of mixtures of vegetable oils is discussed.

About the authors

K. V. Berezin

Saratov State University

Email: dcn@yandex.ru
Russian Federation, Saratov, 410012

K. N. Dvoretskii

Saratov State Medical University

Author for correspondence.
Email: dcn@yandex.ru
Russian Federation, Saratov, 410012

M. L. Chernavina

Saratov State University

Email: dcn@yandex.ru
Russian Federation, Saratov, 410012

A. V. Novoselova

Saratov State University

Email: dcn@yandex.ru
Russian Federation, Saratov, 410012

V. V. Nechaev

Saratov State Technical University

Email: dcn@yandex.ru
Russian Federation, Saratov, 410054

E. M. Antonova

Astrakhan State University

Email: dcn@yandex.ru
Russian Federation, Astrakhan, 414056

I. T. Shagautdinova

Astrakhan State University

Email: dcn@yandex.ru
Russian Federation, Astrakhan, 414056

A. M. Likhter

Astrakhan State University

Email: dcn@yandex.ru
Russian Federation, Astrakhan, 414056

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