Raman spectroscopy study of edible oils and determination of the oxidative stability at frying temperatures

Abstract

Samples of edible oils of different degrees of unsaturation were studied by Raman spectroscopy. We demonstrate the potential of this technique for discriminating these oils. In addition, the Raman spectra for the macadamia, pecan, and Brazil nut oils are for the first time reported here. The fatty acid profile of each type of oil was established by GC. The analytical results obtained from the spectra were highly correlated with those provided by GC as regards the contents in monounsaturated and PUFA of each oil type. Spectra were examined separately in the wavenumber zones 2800-3100 and 800-1800 cm À1 , which were those exhibiting the greater differences between oils. Also, as shown in this work, Raman spectroscopy is an effective tool for assessing oxidation in various grades of olive oils. Based on the results, extra virgin olive oil efficiently resists oxidation in the short term by virtue of its increased antioxidant contents.Practical applications: In this paper we show the usefulness of Raman spectroscopy to distinguish between edible oils. Similarly, the technique also allows us to discriminate between different heat-treated olive oils. At the industrial level Raman spectroscopy can be a useful tool to detect adulteration related to the oxidation of fat. Its ease of use and the absence of sample handling make it very effective for use in production systems on-line.

Virgin Olive Oil as Frying Oil

“…It is worth noting at this point that data obtained for the majority of oil deterioration parameters agree with those provided for TPM and thus support the evidence regarding the good olive oil stability during frying. With respect to the comparative performance of different olive oil types, data obtained by Raman spectroscopy indicate that under heating EVOO performance is superior to that of olive oil and pomace oil; this behavior has been attributed to the higher antioxidant content of EVOO, although the fatty acid composition has to be considered in such comparisons (Carmona and others ). In the study of Casal and others (), the performance of several commercial olive oil types under domestic deep frying of potatoes was investigated and additionally compared with that of a vegetable oil blend principally consisting of sunflower oil.…”

Comparison of the oxidative stability of soybean and sunflower oils enriched with herbal plant extracts

“…To determine of the oxidative stability of oils, as well as the antioxidant effectiveness of spices and herbs many methods and techniques were adopted. The most popular methods are peroxide value and conjugated diene determinations, gas chromatography, chemiluminescence, Raman spectroscopy, or Rancimat test (Farhoosh 2007 ; Carmona et al 2014 ). Among them, also differential scanning calorimetry (DSC) is the most used analytical instrument for studies of physical properties and thermo-oxidative decomposition of native and inhibited fats and their blends (Thurgood et al 2007 ; Kozłowska et al 2014 ; Tengku-Rozaina and Birch 2016 ).…”

Heating Effects of Desi Ghee Using Raman Spectroscopy

“…27 The peak at 1258 cm −1 shows C = C–H bending unsaturation. 24 Raman bands at 1300 cm −1 show in-phase methylene twist (CH 2 ) labeled for unsaturated fats, the band at 1440 cm −1 (δ(C–H) scissoring of –CH 2 ) is labeled for saturated fatty acids, at 1525 cm −1 it represents beta carotenoids, and at 1747 cm −1 it shows ester ν(C = O) Triacylglycerol. 17 The Raman band at 1602–1605 cm −1 shows aromatic ring stretch, C = C bending.…”