Pectin is a carbohydrate in the cell wall of plants. It is a breakdown product from hemicelluloses (protopectins) which is generated during ripening of the fruit. Pectin itself is later broken down to pectinic acid and finally pectic acid. During this chemical breakdown process, the fruit gets softer as the cell walls degenerate.

Apples, plums and oranges contain high pectin, while soft fruits like cherries and strawberries contain few.

Under acidic conditions, pectin forms a gel. This effect is used for making jams and jellies.