- Food History: Douzhi (Mung bean Milk) : Beijing has a long history of making mung bean milk. As early as in the Liao (907-1125) and Song (960-1279) dynasties, mung bean milk was very popular. Local people of Beijing love to drink mung bean milk, because it is rich in protein, vitamin C and rough fiber and helps drive away summer heat, invigorate the function of the spleen and whet the appetite.