| Lecithin can improve the production performance of animal if lecithin is added in the feed, however expensive lecithin can increase costs and reduce economic benefits. In our country egg production is the first in the world, so the egg yolk is an important source of lecithin production, it has high contents of lecithin about 9.76% of the weight of egg yolk also phosphatidylcholine in the egg yolk lecithin is triple of soybean lecithin. But egg yolk lecithin has more cholesterol than soybean lecithin, eating too much cholesterol is not healthy. Some organic solvents such as acetone, diethyl ether and so on, are utilized in the process of lecithin production, that means huge potential security problems.This experiment mainly studied the method of preparation of egg yolk lecithin. Research is undertaken on four aspects: coarse extraction of egg yolk lecithin, removal of triglycerides, cholesterol removal and the refinement of egg yolk lecithin, to establish lecithin production process which is low cost, no toxic solvents, no cholesterol, simple, efficient, economic and suitable for mass production.First of all, lecithin can be extracted from egg yolk because it is easy to dissolve in alcohol. During the extracting process, four main factors including ratio of solid to liquid, ethanol concentration, exacting time and temperature were studied by using single factor analysis method. Then through the orthogonal experiment found that the primary factors which influenced the egg yolk lecithin coarse extraction rate was exacting time and temperature. The best process conditions for: extracting time 60 min, extracting temperature 35 ℃, 95% ethanol concentration, solid-liquid ratio 1:12. Extraction ratio of the egg yolk lecithin crude product was about 25.18%.Second, low temperature cold crystallization method is used to remove triglycerides. After being placed in the low temperature crystallization precipitation throughout the night at the condition of 4℃, solution of triglycerides will stand. Through the use of centrifugal after can remove most of triglycerides. In the before and after the test detect the content of triglycerides in the egg yolk lecithin, and its removal rate was 58.96%.Third, conditions of application of β-CD removal from cholesterol in the egg yolk lecithin process were studied. Made up its saturated solution of β-CD and mixed with the egg yolk lecithin ethanol solution. Application of β-CD to remove cholesterol and compare the effect of different conditions on the removal rate of cholesterol, using TLC and saponification colorimetry to detect cholesterol. In this method the adsorbent dose, adsorption temperature and adsorption time on cholesterol removal effect was researched. The optimized result showed that with additive of 1.6 g cyclodextrin for 10 g fresh egg yellow liquid after ethanol extract lecithin, removal rate is 99.00%.Finally, the egg yolk lecithin will be refined after removal of triglyceride and cholesterol. The isoelectric point of the egg yolk lecithin was 6.7 in the solution, so we can use a buffer to refined egg yolk lecithin. This experiment chose 1/15 mol/L phosphate buffer from three different kinds of buffer with egg yolk lecithin ethanol solution in a ratio of 1:2 mixed, we can get the egg yolk lecithin its purity of 81.32%. The PC content is 56.14%, PE content is 25.18%. |
