| Phosphatidylcholine (PC) is an important physiological active substance, has been widely used in food, health products, pharmaceuticals, cosmetics and other industries. PC originates from the soybean and the yolk at present. The phospholipid of rape oil and the soybean phospholipid has the similar chemical composition, but the sulfuric glucoside and phytic acid in the phospholipid of rape oil has limited its development and utilization. With the double low rapeseed is widely planted, the rapeseed oil lecithin is one of the important resources of the edible commodity of lecithin. Our country is abundant in rapeseed oil sediment resources. Hence it is a direction of rapeseed to make use of rapeseed oil lecithin to prepare PC, which is cheap and valuable.In this research, using ultrasonic extraction method of extracting lecithin powder with the special resource of rape oil residue being raw material was proposed. On the basis of single factor experiments, the response surface method (RSM) was adopted to build a second order quadratic equation for ultrasonic-assisted extraction of lecithin powder. With the lecithin yield as the response index, the result showed that the optimum extraction condition was obtained as follows: ratio of liquid to solid of 6.4mL/g, extraction time of 9 minutes, extraction temperature of 32℃and ultrasonic power of 86 W. Under the optimum condition, the phospholipid yield was 91.06%. The optimized model by the RSM agreed well with practice. The ultrasonic-assisted extraction was more effective with lower extraction time than conventional extraction techniques.Using ultrasonic-assisted, powder lecithin was extracted with ethanol. The best conditions for the ultrasonic-assisted extraction techniques of PC in single factor experiments were: ratio of liquid to solid of 6 mL/g, ethanol concentration 95%, ultrasonic power 200 W, extraction temperature of 30℃, extraction time of 30 minutes, and times of extraction is twice. With the purity and rate as the response value, the functional relationship between main factors and response value were established, and the regression equation was obtained. The extraction parameters were optimized by the RSM as follows: extraction time of 29 minutes, extraction temperature of 30℃, and ethanol concentration of 97% and solid-liquid ratio of 6.2. The optimized extraction rate could reach 50.67% and the purity was 45.13%.To optimize an inductively coupled plasma atomic emission spectrometry (ICP-AES) of the different digestion methods (dry ashing and wet digestion) on the determination of the phosphorus content of phospholipid powder and then to determine the best measurement.The effects of different detection method (ICP-AES and Molybdenum blue spectrophotometry) were compared in the aspect of linear relationship, precision and accuracy. The linear range of phosphorous was 0~100mg/L (R~2= 0.9999); the precision (RSD) of Molybdenum blue spectrophotometry, dry ashing and wet digestion were2.56%, 1.47% and 1.31%; the recovery of Molybdenum blue spectrophotometry, dry ashing and wet digestion were in the range of 94.96%~100.22%, 96.76%~101.73% and 98.87%~102.36%; the detection limit of phosphorous was 20.37μg/L. There is no clear effect to use ICP-AES method and Molybdenum blue spectrophotometry to measure the content of phosphorous. The recovery and precision of ICP-AES are both up to the requirement. The method is simple, rapid and reliable with low direction limit.
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