| Soybean phospholipids are purely-natural products and have been extensively used in many fields,such as the food,medicine,animal husbandry and Cosmetic.And studies show that phosphatidylcholines(PC) which constitute the major phospholipid class of soybean has many physiological functions.In this paper,the PC fractions were successfully extracted from soybean phospholipids as raw materials using supercritical CO2 ultrasound-associated extraction and precipitation with metal ion.The main factors affected the extraction rate and purity of PC were studied and discussed.The PC fractions were successfully extracted from soybean phospholipids with a unique two-step process,consisting of a first step with ethanol as a pretreatment solvent and a second step with supercrirical CO2 extraction.Results of the single factor experiment and orthogonal test showed that in the first step the ratio of solid to liquid had a significant effect,and then was the pretreatment temperature and pretreatment time,and in the second step the extraction pressure had a significant effect,and then was the extraction time and extraction temperature.The optimum conditions were as follows: pretreatment temperature was 30℃,pretreatment time was 60 minutes,ratio of solid to liquid was 0.125 g·mL-1 and the extraction temperature was 50℃,extraction time was 35 minutes and extraction pressure was 35 MPa.Under optimum Conditions,the final yield in our experiments was 84.6%and the PC purity is 87.5%.The uniform design was used to optimize the supercritical CO2 extract conditions and then the mathematical model was established by the DPS data processing:system.And higher purity and yield of PC was obtained.The optimum conditions were:pretreatment temperature was 20℃,pretreatment time was 65 minutes,ratio of solid to liquid was 0.12 g·ml-1 and extraction temperature was 42.5℃,extraction time was 60 minutes,extraction pressure was 42.5 MPa.In the optimum conditions,the yield was 85.84%and the PC purity was 87.8%,Compared with the results of the orthogonal test,the final yield was 1.24%higher than the yield using the orthogonal test.As a result,the method of uniform design had an advantage over the orthogonal test in the analysis of a large number of trials.The technics of ultrasound-associated extraction of PC from soybean phospholipids were studied.The optimal conditions of the main factors were obtained by orthogonal method.At last,the PC was purified by precipitation with metal ion.Results presented demonstrated:that the optimal conditions were:concentration of ethanol was 95%, extraction temperature was 20℃,extraction time was 40 minutes;2 times and the ratio of liquid to material 0,1 g·mL-1.The volume ratio of precipitator and PC solvent which was Obtained by the technics of ultrasound-associated extraction is 1:50 and pH was 9.0.Under this condition the PC purity is 75.3%,the yield is 27.63%.The qualitative and quantitative analysis of different extracted PC fractions was carried out by thin-layer chromatography(TLC),ultraviolet spectrophotometry and high performance liquid chromatography(HPLC).
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