Sources of food
Most food has its origin in plants. Some food is obtained directly from plants; but even animals that are used as food sources are raised by feeding them food derived from plants. Cereal grain is a staple food that provides more food energy worldwide than any other type of crop. [2] Corn (maize) , wheat , and rice – in all of their varieties – account for 87% of all grain production worldwide. [3] [4] [5] Most of the grain that is produced worldwide is fed to livestock. Some foods not from animal or plant sources include various edible fungi , especially mushrooms . Fungi and ambient bacteria are used in the preparation of fermented and pickled foods like leavened bread , alcoholic drinks , cheese , pickles , kombucha , and yogurt . Another example is blue-green algae such as Spirulina . [6] Inorganic substances such as salt , baking soda and cream of tartar are used to preserve or chemically alter an ingredient.