Study On The Separation And Functional Properties Of Active Components From Egg Yolk

Egg yolk, which has high nutritional value, contains excellent proteins and abundant lipids (about 30% of the total egg yolk) including plenty of lecithin and unsaturated fatty acids. So scholars focused on the exploitation and utilization of egg yolk component. In this paper, the technology of purification of egg yolk oil, cholesterol and lecithin from the fresh egg yolk had been improved.Firstly, solvent extraction was carried on using 95% ethanol. The results showed that: 95% ethanol as extraction agent, the ratio of egg yolk to ethanol was 1:10(g:ml),extraction temperature was 65℃, extracting 2 times for each 1 h, the two ethanol extract were pooled together. The yield of egg yolk lipid was 95.40%, then keep the ethanol extract at 4℃for 10 h and respectively recover precipitate (triglyceride, which was insoluble in the ethanol) ,the main component of the precipitate was triglyceride. And other components were phospholipids and cholesterol.Secondly, The conditions cholesterol removal from the ethanol supernatant (which was mainly consist of phospholipids and cholesterol) were as follows: the molar ratio ofβ-cyclodextrin and cholesterol 5.33, the amount of adding water 15g /gβ-cyclodextrin(as the ethanol concentration was 91.1%)the temperature 50℃,contact time 30min. The ratio of cholesterol removal was 96.12%.Thirdly, the recycle ofβ-cyclodextrin and cholesterol was studied. About 97.53% cholesterol could be desorbed fromβ-cyclodextrin- cholesterol complexes when the regurgitant time 2h, temperature 95℃and the ratio ofβ-cyclodextrin-cholesterol complexes to ethanol was 1:10.the purity ofβ-cyclodextrin was 91.31%, which indicating the reuse ofβ-cyclodextrin.The purity of lecithin was 51.47% followed by rotary evaporation. Meanwhile the purification of lecithin was carried on at the temperature of 50℃, adding water 77.85g /g lecithin, contact time 30 min, the purity of lecithin achieved 87.64%, and the yield of phosphorus was 81%.Finally, the denatured egg yolk protein concentrate was studied. The results of DSC showed that the denatured temperature of the protein concentrate was 53℃, while there was no viscoelasticity by the scanning of rheology. The hydrolysis of this protein concentrate was preliminary studied. When the hydrolysis was conducted according to the following conditions: temperature was 60℃, pH was 8.50, the enzyme dosage was 8%, substrate concentration was 2.75%, hydrolysis time was 4 hours, the calcium-binding of the hydrolysis product capacity was 179 mg/ 100g protein.