Infrared spectroscopy in the study of edible oils and fats

Abstract

The use of infrared spectroscopy in the study of fats and oils is reviewed. The importance of the mid‐infrared region in the study of lipids is shown. Differences between dispersive and Fourier‐transform infrared techniques are commented on and the experimental methods used in the handling of oil and fat samples are reported. The assignment of oil and fat bands of mid‐infrared spectra is made, and the usefulness of this technique to characterise oils and fats and to detect adulterations is reviewed. The application of spectroscopic data to determine the degree of unsaturation or iodine value, trans‐ double bonds content, free fatty acid content, average chain length or saponification number, solid fat content, as well as peroxide and anisidine values, is commented on. Also, the importance of this technique for monitoring oxidation processes is shown. © 1997 SCI.

Chemical, thermal and viscous characterization of high-oleic sunflower and olive pomace acid oils and derived estolides

“…The numberaverage molecular weight (M n ), the weight-average molecular weight (M w ), and polydispersity index showed the typical characteristic absorption bands associated with common oils. Thus, the absorption band at around 3550 cm -1 is due to the OH stretching vibration mode of mono or diglycerides or water in acid oil samples (van de Voort et al, 1994), the band at 3005 cm -1 has been assigned to the =CH cis stretching vibration (Guillen and Cabo, 1997) and triglyceride ester carbonyl group gives an absorption band at around 1744 cm -1 . A typical C=O absorption of free fatty acids is found at around 1712 cm -1 .…”

The Detection and Quantification of Adulteration in Olive Oil by Near-Infrared Spectroscopy and Chemometrics

“…Foods and other compounds of bio origin, mainly composed of lipids, carbohydrates, proteins, and water, give rise to absorptions characteristic of these components. [7][8][9][10][11] The use of MIR in the analysis of oils and fats goes back to 1955. 2 A number of MIR spectra of fats and oils have been reported.…”

“…This includes the use of infrared spectrometry, both in the mid-and near-infrared regions. 7 The mid-infrared (MIR) region where the fundamentals of functional groups appear has long been used for food analysis. Foods and other compounds of bio origin, mainly composed of lipids, carbohydrates, proteins, and water, give rise to absorptions characteristic of these components.…”

“…An overview of the applications of MIR spectroscopy to oils and fats can be found elsewhere. 7 The overtones and combinations of the functional groups CH, OH and NH present in food samples give rise to absorptions in A new procedure has been developed for the classification and quantification of the adulteration of pure olive oil by soya oil, sun flower oil, corn oil, walnut oil and hazelnut oil. The study was based on a chemometric analysis of the nearinfrared (NIR) spectra of olive-oil mixtures containing different adulterants.…”

Synthesis and microstructural characterization of kaolin-polyethylene composites

“…3 , respectively by Guillen and Cabo, [20]. The absorption of carbonyl (C@O) groups from ester linkage of triglycerol of coconut oil is usually observed around 1732 cm 21 with a strong intensity due to the great difference in electronegativity between the carbon and hydrogen atoms as reported by Pavia et al, [21] are attributed from the vibrations of stretching mode from the CAO group in esters, Silverstein and Webster [22].…”