Separation and characterization of pigments from bleached and deodorized canola oil

Abstract An analysis of pigments responsible for color formation during bleaching and deodorization of canola oils treated with activated bleaching earth (ABE) or novel mineral‐acid/silica (AS) adsorbents is presented. The chromophores are trace glycerides and were concentrated by silica column chromatography. The concentrated color bodies were hydrolyzed and analyzed as free acids or methyl esters by reversed‐phase high‐performance liquid chromatography with photodiode array and mass spectrometry detection, 1 H and 13 C nuclear magnetic resonance and infrared spectroscopies. Absorbance in deodorized oils is mostly from oxygenated C18 and C20 fatty acids with 1 to 4 double bonds. High‐wavelength absorbance in AS‐bleached oils is from conjugated pentane fatty acids that are not observed for ABE‐bleached oils. Thus, both the bleaching agent and the deodorization treatment affect the distribution and concentration of such stable chromophores.