Purification process of octacosanol extracts from rice bran wax by molecular distillation

Molecular distillation (MD) was used to increase the purity of octacosanol extracts from transesterified rice bran wax (RBW), and the effects of MD parameters on the purification process and efficiency were studied. The octacosanol content, triacontanol content and the ratio of octacosanol content (Co) to triacontanol content (Ct) in distillates and residues, the yields of distillates and residues, and split ratio (yield of distillates to the yield of residues) were investigated in the circumstance of temperature and pressure changes. Results indicated that distilling temperature and distilling pressure are very important factors in purification process. The increase of distilling temperature or the decrease of distilling pressure could increase the mean free path (MFP) of molecules; therefore, the components with larger molecular weight could be separated and concentrated onto the condenser, and the yield of distillates increased and the split ratio was higher, but the content of octacosanol in distillates did not increase accordingly. Purified by MD at 150 °C and 0.5 Torr, the octacosanol content in distillates can be up to 37.6%, increasing by 48.0% over that in the raw octacosanol extracts. The purification processes of octacosanol extracts with MD were further explained by comparing the components of distillates with residues at 0.5 Torr, and the components of distillates at 0.5 Torr with those at 2.0 Torr as well.