Studies On Purification Of Plant Sterol

A process for extracting plant sterol from plant oil deodorizer distillate (PODD) was studied in this paper. The process includes transesterification of sterol ester in PODD and purification of sterol from the product of transesterification by extraction and crystallation.After the pretreatment of PODD,sterol ester in PODD can be transesterified into free sterol with methanol while methanolic sodium as catalyst. The effect of proportion of methanol to oil, proportion of methanolic sodium to oil, reaction temperature, reaction time was studied. The results show that enhancing temperature and prolonging the contact time are in favor of the reaction, till it gets to the equilibrium of conversion. Furthermore, the optimal condition for transesterification of sterol ester has been obtained as followed: CH3OH:PODD=0.8(w/w), NaOCH3:PODD=0.01(w/w), 61癈, 2 hour. While under this condition, 93% as the ratio of transesterification was obtained. And the kinetic of reaction was also studied, the apparent equation of reation is shown as followed:The extraction from the transesterified substance was studied. Sterol was obtained mostly by crystallation. After exaction, the purity of sterol producted by crystallation may get to 90% above.While n-hexane was used as much as 2-3ml/g oil, the purity even may get to 99%..The purification of sterol product was studied by recrystallation.When the solvent was chosen as acetone or n-hexane, the iniatial temperature was set on the close boiling point of the solvent. 54癈 or 65癈.The final temperature was set on 5癈.The purity may both get to 99%.The range of melting point of sterol product was determined as 127-132癈.