Analysis of the content of oleic and linoleic fats in a binary mixture of vegetable oils using Raman spectroscopy
Ekaterina M. Antonova, K. V. Berezin1, A. M. Lichter2, V.V. Nechaev3, K. N. Dvoretski4;
1Institute of Physics, Saratov State University, Russia
2Astrakhan Tatishchev State University, Russia,
3Yuri Gagarin state technical university of Saratov, Russia,
4Saratov State Medical University, Russia
Abstract
Raman spectra of five sunflower seed oil samples and five cold-pressed olive oil samples of different brands were recorded in the range of 500−2000 cm−1. Structural models of eight fatty acids were constructed using 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: oleic, linoleic, palmitic, stearic, alpha-linolenic, arachidonic, eicosapentaenoic, and docosahexaenoic acids, as well as triglycerides of the first four of the above-described acids, using the B3LYP/6-31G(d) method. Vibrational wave numbers and intensities in the IR and Raman spectra were calculated. Using the supermolecular approach, Raman spectra of olive oil and sunflower seed oil were simulated. The dependence of the relative intensity of the vibrational bands νexp = 1660 cm−1 and νexp = 1445 cm−1 on the content of oleic and linoleic acid triglycerides in the oils was studied. The dependence of the intensity of these bands on the degree of saturation of fatty acids was studied. Experimental and empirical dependences were constructed to estimate the relative content of oleic and linoleic acid triglycerides in a mixture of olive oil and sunflower seed oil. The applicability of density functional theory methods together with vibrational spectroscopy for determining mixtures of vegetable oils was discussed.
Speaker
Ekaterina M. Antonova
Saratov State University
Russia
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