Study On Preparation And Amplification Of High - Purity Plant Sterol Ester

Phytosterols are attracted widespread attention in recent years for the prevention of cardiovascular disease which is used as a kind of functional food. They can also be treated as "the key of life". But the utllizations of free phytosterols were limited because of its low fat-solublity. The synthesis of phytosterol esters can greatly improve their oil-soluble and the activity has not been changed. So phytosterols usually used in the form of phytosterol esters in the commercial application. Early, we have synthesized phytosterol oleic esters through esterification of phytosterol with oleic acid by autocatalytic process. In order to reduce the side-effect on esterification reaction and the impurity in product composition. In this paper the raw phytosterol was purified by crystallization firstly, the phytosterol ester was synthesized through the purified phytosterol with oleic acid and the amplification experiment was carried out.The solubility of phytosterol in different solvents for phytosterol crystallization were determined. A suitable solvent of n-hexane/ethyl acetate mixed solvent was selected. Phytosterol was separated and purified from raw sterol through crystallization based on the different solubilities of phytosterol under temperature changing. Some parameters(ratio of mixed solvents, ratio of phytosterol to solvent, crystallization temperature and crystallization time) were optimized for crystallization of phytosterol as the follows:ratio of n-hexane to ethyl acetate was 1:2, ratio of phytosterol to solvent was 1:15, crystallization temperature was 5℃ and crystallization time was 4 h. Under above conditions,the purity of sterol is about 98.23%, the recovery is 83.21%.Phytosterol oleic esters was synthesized with oleic acid and phytosterols with different purity sterols. The results show that:oleic acid/phytosterol mole ratio of 2.96:1, the reaction temperature was 220℃, the reaction time was 4 h, the conversion was 99.39% and the yield was 86.51% when the purity is 89.65%; the conversion was 99.33% and the yield was 93.62% when the purity is 95.40%; the conversion was 99.30% and the yield was 96.78% when the purity is 98.30%. The yield and selectivity were improved obviously with the improvement of purity of phytosterols.On the basis of a lab-test, further amplification reaction was investigated. The reaction was amplified 10 times. Phytosterol ester synthesis heat enthalpy was calculated about -2.45KJ·mol-1. Compared with the lab-test, the amplification reaction time was shorten for the thermal effect. The optimum reaction conditions:reaction temperature 220℃, reaction time 2 h was carried out. The phytosterol conversion was 98.20%, the yield was 84.30%, product purification after the actual yield is 75%. This work was laid a foundation for production of phytosterol oleic esters.