SEPARATION AND CHARACTERIZATION OF PIGMENTS FROM BLEACHED AND DEODORIZED CANOLA OIL

An analysis of pigments responsible for color formation during bleachi ng and deodorization of canola oils treated with activated bleaching e arth (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 a nd analyzed as free acids or methyl esters by reversed phase high perf ormance liquid chromatography with photodiode array and mass spectrome try detection, H-1 and C-13 nuclear magnetic resonance and infrared sp ectroscopies. Absorbance in deodorized oils is mostly from oxygenated C18 and C20 fatty acids with 1 to 4 double bonds. High-wavelength abso rbance in AS-bleached oils is from conjugated pentane fatty acids that are not observed for ABE-bleached oils. Thus, both the bleaching agen t and the deodorization treatment affect the distribution and concentr ation of such stable chromophores.