2. Turn off the fire and simmer for two or three minutes, then boil the pot to see if the noodles change color. If the color is still not completely changed, cook for a while until it becomes a mature color. Coarse cereal noodles (including corn noodles and sorghum noodles) are generally difficult to cook, and the cooking time is a little longer. Noodles don't have to worry about cooking, generally they don't rot easily.