Any of a class of carbohydrates found in certain plant cell walls and tissues. They are principally composed of a galactose derivative, galacturonic acid. In fruits, pectin keeps the walls of adjacent cells joined together, helping them remain firm and hold their shape. As fruits become overripe, the pectin breaks down to simple sugars that dissolve more readily, so the fruits become soft and lose their shape. Because it forms a thick, gel-like solution when added in small amounts to fruit acids, sugar, and water, pectin is used to make jellies, jams, and marmalades. Its thickening properties also make it useful in the confectionery, pharmaceutical, and textile industries.