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. 2022 Jul 8:17:100386.
doi: 10.1016/j.fochx.2022.100386. eCollection 2023 Mar 30.

Study of vegetable oils and their blends using infrared reflectance spectroscopy and refractometry

Almas Mukhametov  1 , Laura Mamayeva  1 , Assemay Kazhymurat  1 , Togzhan Akhlan  1 , Moldir Yerbulekova  1
Affiliations

Study of vegetable oils and their blends using infrared reflectance spectroscopy and refractometry

Almas Mukhametov et al. Food Chem X. .

Abstract

The present study aims to perform a comparative analysis of vegetable oils and their two-component blends using infrared spectroscopy and refractometry. The study was conducted in Almaty (Kazakhstan) in 2020. Three samples of 44 vegetable oils and their blends made from two components were examined. Fractometry and infrared spectroscopy were used to investigate the properties of blended vegetable oils. To this end, the fatty acid fraction (in percentage), iodine number, and index of refraction (IOR) were calculated. Afterward, the spectrograms obtained for the blends were analyzed. It was found that the difference between the intensities of weak bands and the band expansion of 722 cm-1 indicates greater expressiveness. When low-intensity bands (1653 cm-1) become more distinct due to vibrations of double carbon bonds (C-bonds), the level of unsaturated fatty acids in the blend increases as well.

Keywords: Blends; Infrared spectroscopy; Refractometry; Spectrograms; Vegetable oils.

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Conflict of interest statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Fig. 1
Fig. 1
Correlation between iodine number index and IOR for the four studied groups of vegetable oils (1 – oleic acid, 2 – linoleic acid, 3 – linolenic acid, 4 – palmitic acid).
Fig. 2
Fig. 2
Two-component blends according to refractometry-based analysis: the base is (a) olive oil, (b) sunflower oil, (c) flaxseed oil. The second component was 1 – flaxseed, 2 – grapeseed, 3 – cedar nut, 4 – sunflower, 5 – mustard, 6 – olive, 7 – ginger.
Fig. 3
Fig. 3
Fragments of the infrared spectra presented in Fig. 3: 1 – flaxseed, 2 – cedar nut, 3 – olive, 4 – palm oils; (a) C and H2 groups (corresponding to 2923 cm−1 and 2853 cm−1 bands), C and H groups (with bivalent C-bond, corresponding to 3008 cm−1 band); (b) C and H2 groups with bivalent C-bond (corresponding to 722 cm−1); (c) bivalent C-bonds (corresponding to 1653 cm−1).
Fig. 4
Fig. 4
Band intensity changes in the infrared spectrum of 4 vegetable oils: 1 – olive, 2 – cedar nut, 3 – flaxseed, 4 – palm oil; (a) 1653, 722, and 3008 cm−1, (b) 2,923 and 2853 cm−1.
Supplementary figure 1
Supplementary figure 1
Infrared spectra of vegetable oils belonging from 4 groups: 1 – olive, 2 – cedar nut, 3 – 453 flax seed, 4 – palm oil.
Supplementary figure 2
Supplementary figure 2
Relationship between the iodine number and band maxima for (a) 3,008 cm-1; (b) 1,653 cm-1; (c) 2,923.
Supplementary figure 3
Supplementary figure 3
Fragments of the infrared spectra for blends from Series 1 (olive and flaxseed oil) for different IOR values (a-c): line 1 – 0 %, line 2 – 30 %, line 3 – 50 %, line 4 – 80 %, line 5 – 100 % of flaxseed oil.
Supplementary figure 4
Supplementary figure 4
Fragments of the infrared spectra for blends from Series 1 (flaxseed and olive oil) for different IOR values (a-c): line 1 – 0 %, line 2 – 30 %, line 3 – 50 %, line 4 – 80 %, line 5 – 100 % of olive oil.
Supplementary figure 5
Supplementary figure 5
Changes in the expressiveness of bands in the infrared spectrum for blends in Series 1 (1, 2) and 2 (3, 4).
Supplementary figure 6
Supplementary figure 6
Shifts in values of 3,008 cm-1 (a) and 722 cm-1 (b) bands associated with the components of Series 1 and 2.
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