INFRARED-SPECTROSCOPY IN THE STUDY OF EDIBLE OILS AND FATS

The use of infrared spectroscopy in the study of fats and oils is revi ewed. The importance of the mid-infrared region in the study of lipids is shown. Differences between dispersive and Fourier-transform infrar ed techniques are commented on and the experimental methods used in th e 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 t his technique to characterise oils and fats and to detect adulteration s is reviewed. The application of spectroscopic data to determine the degree of unsaturation or iodine value, trans-double bonds content, fr ee fatty acid content, average chain length or saponification number, solid fat content, as well as peroxide and anisidine values, is commen ted on. Also, the importance of this technique for monitoring oxidatio n processes is shown.