Study On The Extraction Process For Lecition In Egg Yolk

In order to get a simple, efficient, and economical extraction method for massproduction of egg yolk lecithin （EYL）,the detailed process was studied in thisexperiment.This research included EYL test methods, extraction methods and extractionconditions.Three test methods for EYL were studied: molybdenum yellow colorimetry,ultraviolet spectrophotometry and thin layer chromatography(TLC). The total content ofEYL was determined by molybdenum yellow colorimetry, and in this method the influenceof different zinc oxide content on molybdenum yellow colorimetry was mainly researched.The qualitative and quantitative analysis of phosphatidylcholine (PC) as lecithin majoringredient was determined by ultraviolet spectrometry. The qualitative analysis of PC andPE (phosphatidylethanolamine) was determined by TLC, that focused on three aspects:developing solvent preparation, thin layer plate activation method and tomographic time.On the basis of organic solvent extraction, this experiment compared the ethanolextraction method, ethanol-acetone extraction method and acetone-ethanol extractionmethod, and studied the effect of ethanol concentration on the extraction of lecithin.At lastthe extracted lecithin was detected by the established test methods.The main experiment content and conclusions as follows:1. The three test methods were coordinated with each other to detected the quality andquantity of EYL. In the molybdenum yellow colorimetry,0.1g sample needed1g zincoxide to assist in ashing, the phosphorus standard curve was y=18.485x+0.0135，and thelinear relation was good.The ultraviolet scanning figure of egg yolk PC standard substancewas good:the maximum absorption was210nm, the ultraviolet absorption standard curvewas y=3.6915x+0.0077, and the ultraviolet spectrophotometry had high repeatability andstability.In the TLC method, the developing solvent system was:V(chloroform)：V(carbinol)：V(water)=65：25：4，the thin layer plate activation method was105℃1h,and the tomographic distance was10cm.2. The optimum ethanol concentration varied with different extraction method. Ethanol wasthe preferred solvent in lecithin extraction, but different methods had different optimumethanol concentration. The optimum ethanol concentration of ethanol extraction methodand ethanol-acetone extraction method was95%, and acetone-ethanol extractionmethod was90%. 3. The extraction order of ethanol and acetone determined the purity and amount of EYL.Ethanol was an effective solvent to extract EYL, acetone could enhance the lecithin purityremarkably. Comparing with ethanol-acetone extraction method, acetone-ethanolextraction method could get higher purity, but the amount was lower.Therefore,taking thetwo factors of purity and amount together, ethanol-acetone extraction method was theoptimal method. The ultraviolet scanning figure of extracted lecithin was good,thatcoincided with the standard substance of EYL with the maximum absorption wavelengthof210nm. In the TLC pictures of extracted and standard lecithin, PC and PE as lecithinmain ingredients both had the same location correspondingly, and the purity ofextracted lecithin was much higher.4. The influence of egg yolk pretreatment on EYL extraction: the experiment adopted threepretreatment methods: egg yolk powder, fresh egg yolk and freeze thawing egg yolk,theresults showed that freeze thawing egg yolk had the best extraction effect.