Food

Food is composed of many different chemical substances major nutritional components that are present in relatively small amounts, such as vitamins, water, and roughage. Many other components can also be present in food.

Food may contain colours, flavours, pharmacologically active substances, natural toxicants and various contaminants. Even characteristic flavours such as those of oranges and passionfruit can depend on the presence of a dozen or more chemicals. It is also more than just the chemicals it contains. Its physical characteristics are important. The size of food particles can affect the extent to which nutrients are digested and made ready for by the body. For example, eating an intact apple has nutritional value different from drinking all the same chemicals in an apple purée. Ground rice is more rapidly digested than unground rice. Nutrients can be more easily absorbed from peanut butter than from peanuts eaten whole.