After using the vegetable juice, too much water was added to the vegetable juice, which caused the color to fade.

The dough is too soft, and too much dry powder will fade.

Noodles are rolled too thick, and natural pigments are not resistant to high temperature. The longer they cook, the lighter the color.

The practice of colored noodles:

Juice

Use Chinese cabbage, spinach, carrots and amaranth to make juice, or directly mash it into paste.

Knead flour into dough.

Add vegetable juice into proper amount of flour, knead it into dough, and let it stand for proofing.

Pressing/rolling noodles

Roll all the dough into pancakes, and sprinkle appropriate amount of fine noodles on each layer to avoid adhesion. Cut into the required wide and thin noodles. Don't cook noodles for too long.