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1, those deep yellow duck egg yolk and yolk are good sources of lutein and zeaxanthin. Studies have shown that more than one-third of the fat-soluble yellow substances in egg yolk come from these two components, which are easily absorbed by the human body and are better than eating corn directly. Therefore, for normal eggs, the yellower the yolk, the better for eye health.
2. Vitamins are mostly concentrated in egg yolk. Egg yolk contains valuable vitamins A and D, as well as vitamin E and vitamin K, which are "fat-soluble vitamins". Most water-soluble B vitamins also exist in egg yolk. The reason why egg yolk is light yellow is because it contains riboflavin, which is vitamin B2. Can prevent mouth rot, glossitis, cleft lip, etc.
3. Fresh eggs with good quality, with clear colors of yolk and egg white, no abnormal colors, round and convex yolk and toughness; The egg white is thick and thin, with distinct layers, and the lace is thick and tough, close to both ends of the egg yolk.
The color of inferior fresh eggs is normal, and the yolk is round or reticulate blood red; The color of egg white is green, and other parts are normal. Or the color of egg yolk becomes lighter, the color distribution is uneven, and there is a big ring or a reticulate blood red; There are yellow-black sticky marks or mildew spots on the inner wall of eggshell; Egg white and yolk are mixed together.
The liquid in inferior fresh eggs is grayish yellow, grayish green or dark yellow, mixed with black mildew spots, the yolk expands flat, the yolk membrane thickens and turns white, there is a big blood ring in the yolk, a little bloodshot can be seen in or around the ring, the egg white becomes thinner, there are traces of egg yolk adhesion on the inner wall of the eggshell, and the egg white and egg yolk are mixed together (but there is no odor); There are bugs in the eggs.
Or the egg white and yolk become thin and turbid; There are mildew spots in the egg membrane and egg liquid or the egg white is gelatinous mildew spots; Embryo formation and growth.
References:
Baidu encyclopedia-egg yolk