Effect of chemical refining steps on the minor and major components of cottonseed oil

During chemical refining steps (neutralization, bleaching and deodorization) of crude cottonseed oil (CSO), minor and major components, namely, tocopherols, sterols and fatty acids were evaluated by HPLC and GLC. HPLC analysis of total tocopherols (T) revealed that loss in these components were 7.12, 12.28 and 18.47 % in neutralized, bleached and deodorized oil respectively. On the other side, quantitative GLC analysis of sterols (as trimethylsilyl derivative, TMS), showed that the losses were 5.6, 8.7 and 16.4 % at the different refining steps respectively. In case of the fatty acids (as methyl esters, ME), as determined by GLC analysis, it was noticed that essential fatty acids (EFA), namely, linoleic and linolenic were nearly kept constant. The total amounts of sterols and tocopherols lost in the deodorized distillates (D D) as well as their patterns were also determined. It was found that total sterols content was 28500 ppm, whereas tocopherols content was 2640 ppm. Sterenes (reference samples) were also used to follow the formation of sterenes during the chemical refining steps of CSO.