Yu Hongkun is known as "the last descendant of ancient food doctors". What was an ancient food doctor?

"Zhou Li? "Tianguan Zhi": "Doctors are divided into four grades, and' food doctors' are the most important. Six foods, six drinks, six meals, one hundred shames, one hundred sauces and eight treasures are king; Doctors who treat diseases, doctors who choose doctors and veterinarians are all listed under the leadership of food doctors. " "Food doctor" is a special industry engaged in medicinal diet, serving the royal family. Are you satisfied with my answer? If you are happy, adopt it.