The compounds responsible for the colors of palm oils at various stages of processing have been isolated by gel permeation chromatography. The isolated colored compounds have been characterized by visible spectroscopy and, in some cases, further fractionated by high performance liquid chromatography. All palm oils studied contained colored compounds of both higher and lower molecular weight than trigtycerides. Oils at different stages of processing contained different proportions of these high and low molecular weight, colored compounds. While the color of crude palm oils was primarily due to the low molecular weight carotenoids, the color of finished oils was due to compounds other than carotenoids. High molecular weight compounds were significant, sometimes predominant, contributors to finished oil colors. These results demonstrate the importance of high molecular weight, colored compounds to the color of finished palm oils. Further, these results suggest that the difficulties associated with decolorization of certain crude palm oils may be due either to the presence of high molecular weight, colored compounds or to the presence of precursors capable of generating these compounds during the decolorization process.
ABSTRACTTwenty-four oxygenated cholesterols and structurally related compounds were analyzed by high performance liquid chromatography with silicic acid column and various mobile phases. Hexane/2-propanol was superior to hexane/tetrahydrofuran and hexane/ethyl acetate for the separation of oxygenated cholesterols. The retention volumes of oxygenated cholesterols depended on the characteristics of the substituting group, its position of substitution, as well as its orientation. The effect of various functional groups at different positions on cholesterol molecules, in general order of decreasing retention volumes, were: hydroxy on the ring, carbonyl on the ring, epoxy on the ring, hydroxy on the side chain, and carbonyl on the side chain. Synergistic effect of multiple hydroxyl substitutions on cholesterol was observed.