Extraction and identification of lecithin in egg yolk - Master's thesis - Dissertation

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Extraction and identification of lecithin in egg yolk

First, the purpose

Learn about the nature of lecithin. Learn and master the method of extracting crude lecithin.

two,

principle

The various tissues and cells of the body contain lecithin. It is higher in tissues such as egg yolk, nerves, semen, brain, adrenal gland, heart, mushroom and yeast. Pure lecithin is a white waxy block that is insoluble in water and soluble in alcohol, chloroform, and carbon disulfide, but insoluble in acetone. It can be separated from neutral fat by its insoluble ketone

Third, the experimental supplies

1. Experimental materials

egg

2, utensils

Water bath, small beaker 50mL × 1, dry test tube 20mL × 1, 10mL × 2, test tube rack, glass funnel, glass rod, measuring cylinder 25mL × 1, pipette 2mL × 2, 1mL × 1

3, reagents

95% ethanol, 10% sodium hydroxide solution, acetone

Fourth, the operation steps

1, extraction. Take about 2g of egg yolk and put it in a small beaker. Add 15 mL of hot 95% ethanol solution while stirring. After cooling, it was filtered into a dry test tube. If the filtrate is turbid, it needs to be refiltered until it is completely transparent. The filtrate was evaporated to dryness on a water bath.

2. Trimethylamine experiment. Take a portion of the lecithin prepared in step 1 and place it in a test tube. Add 2 mL of 10% sodium hydroxide solution and heat on a water bath. Lecithin decomposes to form choline, which forms trimethylamine under the action of a base. Note that the top three have a fishy smell.

3, another take lecithin dissolved in 1mL of ethanol, add acetone 1 ~ 2mL, observe the change.