Purple potato steamed bread belongs to coarse grains. Generally, steamed bread made of white flour does not belong to coarse grains, but steamed bread made of coarse grains is.

According to the different forms of coarse grains, coarse grains can be roughly divided into three categories:

1. Cereals: corn, millet, Redmi, black rice, purple rice, sorghum, barley, oats, wheat, etc.

2, miscellaneous beans: soybeans, mung beans, red beans, black beans, broad beans, peas and so on.

3. Tubers: sweet potato, yam, potato, etc. The processing of coarse grains is very simple, and it retains many nutrients that are not found in flour and rice. For example, the content of protein in coarse grains is relatively low, while the content of starch, cellulose, inorganic salts and B vitamins is rich.