A simple method to exclude Sudan red. If in doubt, we can see if food coloring is soluble in water. Sudan red is insoluble in water, but soluble in organic solvents such as chloroform.
Pepper noodles without Sudan red are natural and golden in color. After adding Sudan red, the color is bright and unnatural. With the extension of storage time, the color of natural Chili powder will gradually fade, or we will gradually fade when exposed to the sun; However, the color of Chili powder with Sudan red is very bright, and it will not change color after being stored for one year. Citizens can take a container, put a little Chili powder in it, and add some cooking oil to stir. After a few hours, the color of the oil is very red, which may mean that Sudan red has been added. If the color changes little, it means that Sudan red is not added.