Pectin content of apple fruit

Pectin is a plant cell wall polysaccharide consisting of a linear chain composed of D-galacturonic acid residues linked via α(1-4)-glycosidic bonds. Pectin or pectin solutions may be manufactured or obtained from dried apple peels and cores.

When pectin molecules come in contact with fruit acid, chainlike structures in the pectin become charged and these chain fold in on themselves. The folded chains trap water from the fruit or juice, forming gel.

Fruit contains pectin substances in a form that is not water dispersible and in this form cannot be used for the manufacture of jams, jelly, and other foods.

Pectin, which is released from the middle lamella of apple cell was by the mechanical action of milling and pressing is present in all fresh apple juices to a varying extent.

In early season fruit, amounts of soluble pectin may low, in the order of 0.1% by weight of juice. In later fruit, or in fruit from cold store, pectin may rise as high as 1-25% in the juice.

Commercial pectin comes in two forms, liquid and powdered. Liquid and powdered pectins are not interchangeable. Each requires a different balance of fruit, sugar and acid to attain the proper set.
Pectin content of apple fruit