| The research on extraction of ducks yolk lecithinLecithin is a naturally occurring group of posphiolipids found in nearly every living cell. Although the word lecithin is derived from the Greek 'lekithos', which means 'yolk of an egg', at present the primary commercial source of lecithin comes from the soybean. Lecithin obtained from different source is different from component, the physiological activity of yolk lecithin is best. Recently, the demand for yolk lecithin has increased in the fields of food additive, nourishment, cosmetic and pharmaceutical As a food additive, lecithin is primarily utilized as emulsification agents, stabilization agents and wetting agents.At present, the processing techniques of lecithin were as follows: mixture solvent (ethanol-water) extraction, columniation chromatogram, acetylized reaction, HPLC, membrane ultration, supercritical CO2 extraction. By far, yolk lecithin was completely obtained from egg's yolk and nobody researched duck's yolk lecithin. In this study, we used mixture solvent (ethanol-water) to extracte lecithin from duck's yolk because of the following advantages: lesser cost, volatile solvent, safe edibility.According to the past researches, we designed the following processes: freezing and additive salt process, single freezing process, hydrolyzing protein process. We studied the relation between salt, conditions of ethanol extraction (temperature.time, and concentration), conditions of hydrolyzing protein(variety, activity, temperature of enzyme,) and yield, purification of lecithin.In the freezing and additive salt process, yield of lecithin was gradually increased and lecithin was gradually browned, alone with concentration of salt was increased. The yield amounted to 86% when concentration of salt was 3%. But higher concentration of salt affected sensory color of lecithin. What is more, the main defect of additive salt process was leavings of salt. Comparing with freezing and additive salt process, there was a notable decrease on the ashes of lecithin(56.16%) in the single freezing process. It was proved that the remnant ions were mainly CI". In theabstract, freezing may denaturalize protein and destroy emulsification of yolk, but effect of extraction in single freezing process, was ordinarily.The yield of lecithin reached maximum, when concentration of ethanol in yolk was 90%. Lower concentration of ethanol brought air bubble to vacuum condensation operation. Higher concentration made product brown. In case of yield, color of lecithin and economy, two times extraction was adopted. Along with increase of temperature, yield of lecithin was notably increased. But appropriate temperature of extraction was 45 癈, in case of yield , heat-lability of lecithin and heat-away of ethanol dissolving. The time of extraction was 20 minutes.Enzyme exceled freezing in yield of lecithin, but degree of hydrolyzation of protein should be appropriate. When activity of neutral enzyme ranged between 2000 and 60001/1 OOg, D.H. and amino acid nitrogen(AN) were increased. The undissolve substance of acetone and P/N of A B20ooC3ocDi.sh and A oooC45rDi.5h were respectively 94.73%Vs0.95, 92.92.%Vs0.93.The enzyme affected yield of lecith from yield and purification of lecithin.The pancreas could increase yield of lecithin. But neutral enzyme and papain could improve purification of lecithin.Yield of lecithin is best in the process of Aeapsm Booo Ct Dh, and the yiled was 7.68g/100g. The higher yield of lecithin improved the using ratio. By supercritical CO extraction, high purify duck-yolk lecithin sample was obtained. The effect of kinds of protease on the yield of lecithin was the most evident. Among three kinds of enzymes, the yield of pancreas was best. The next effective factor was the hydrolyze time of protease. During yolk was hydrolyzed, at first the yield of lecithin increases, subsequently descended, the yield was the highest at the second hour. The third effect factor was the hydrolyze temperature of enzyme, and the best hydrolyze temperature was 37.5癈. The l...
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