If it takes less than fifteen minutes, the raw meat of undercooked crabs contains a large number of parasites and disease-causing bacteria, which is harmful to the body if eaten. Too long a time will make the taste worse and the meat older.
Before steaming the crab, put the crab into the salt water to soak for at least half an hour, the salt water can stimulate the crab to spit out the body of the dirt, to ensure that the steamed crab out of the clean and sanitary.