Direct monitoring of lipid oxidation in edible oils by Fourier transform Raman spectroscopy.
Fourier transform Raman spectroscopy has been used to investigate the chemical changes taking place during lipid oxidation in several edible oils. Oxidative degradation of six vegetable oils was accelerated by heating at 160 degrees C. Formation of aldehydes was detected, and saturated as well as alpha,beta-unsaturated aldehydes could be identified with the help of pure component spectra. The formation of conjugated double bond systems and the isomerisation of cis to trans double bonds was observed in the C=C stretching region and found to follow a distinct pattern for the different oils. It was possible to associate these differences to the fatty acid composition. The time-dependent intensity changes in certain Raman bands were compared to conventional parameters used to determine the extent of oxidation in oils, such as anisidine value and K(270), and showed good correlation.
Muik
Barbara
B
Department of Physical and Analytical Chemistry, University of Jaén, Paraje las Lagunillas s/n, E-23071 Jaén, Spain.
Lendl
Bernhard
B
Molina-Díaz
Antonio
A
Ayora-Cañada
María José
MJ
D005227:Fatty Acids / Q000032:analysis; D005231:Fatty Acids, Unsaturated / Q000737:chemistry; D005583:Fourier Analysis; D008055:Lipids / Q000737:chemistry*; D010084:Oxidation-Reduction; D010938:Plant Oils / Q000378:metabolism*; D013059:Spectrum Analysis, Raman / Q000379:methods*
D005227:Fatty Acids; D005231:Fatty Acids, Unsaturated; D008055:Lipids; D010938:Plant Oils