The Study On Synthesis Of Phytosterols Ester By Microwave Heating

Phytosterols is one kind of important sterols, including brassicasterol, campesterol, stigmasterol, β-sitosterol. It can be mainly obtained from deodorizer distillate. Phytosterols inhibited the absorption of cholesterol in the human body, is an active ingredient to depress serum cholesterol. But the lower solubility in water and oils restricted its applications, some research indicated that , phytosterol esters have better solubility and more efficient cholesterol-lowering effect than phytosterols, it can be used as functionality food additive. The traditional preparations of phytosterol esters always used the conventional heating sources. Such reactions need long time, and had more causticity to equipments, besides the complicated reactions, the products were difficult to separate. To make more effective use of phytosterols, used microwave as heating sources for phytosterols esterification, microwave heating had uniform speed , highly utilization, it greatly shorten the esterification time , reduced environmental pollution, also had mild reaction conditions and high yields. Thereby, and the analytic methods were studied systematically in this dissertation. The main results are shown as follows: 1. The studies on the esterification process of phytosterols by microwave heating(1) The reaction between phytosterols and acetic anhydridePhytosterol acetates (PSA) were synthesized by direct esterification of phytosterol and acetate acid in the presence of catalyst pyridine. The effects of microwave radiation temperature, reaction time and the amount of phytosterol/acetic anhydride mole ratio were discussed. The results indicated that: when the esterification temperature was 85℃, molar ratio of phytosterols to anhydride acid and catalyst pyridine was above 1:10:12, reaction time was 5 min, the yield of esterification was 96.5%.(2) The reaction between phytosterols and excess acetic acid solutionDiscussed the effects of microwave heating and dosage of phytosterols with acetic acid tothe invert ratio during the esterification process, the best esterification condition were: esterification time 5 min, temperature was 85℃,the dosage of phytosterols with acetic acid was 3g:30mL. The invert ratio was about 93.2%.(3) The reaction between phytosterols and stearic acidPhytosterols stearic (PSS) were synthesized by direct esterification of phytosterols and stearic acid. Through factorial design, the optimal synthetic conditions were obtained as follows: molar ratio of phytosterols to stearic acid was above 1:1.2; reaction temperature was 135℃ and reaction time was 10min. The yield of esterification was 89.7%.(4) The reaction between phytosterols and nicotinic acidUnder the microwave heating, discussed the phytosterol nicotinate esterification, the effects of reaction temperature, microwave radiation time and amount of phytosterols/nicotinic acid mole ratio. The optimum reaction condition were as follows: acylation halide temperature was 50℃, molar ratio of phytosterols to nicotinic acid was about 1:1.4, esterification time was 10min, under this condition the yield of esterification was 92.2%. 2. Study on analytic methods of phytosterols and phytosterol estersThe qualitative and quantitative of phytosterols and phytosterol esters were analyzed by UV, IR, HPLC.The results indicated that: Under the same experimental conditions the maximum absorption wavelength of phytosterols and phytosterol esters were different; in their infrared spectrogram also had the obvious characteristic absorption peaks; phytosterols and phytosterol esters could be separated in different times, the response times were phytosterols20～25min, phytosterols acetate 10～15min, phytosterols stearic 13～18min, phytosterols nicotinate 12～17min.