Pectin is a long chain of pectic acid and pectinic acid molecules. Because these acids are sugars, pectin is a polysaccharide. It is prepared from citrus peels and the remains of apples after they are squeezed for juice.
In the plant, pectin is the material that joins the plant cells together. When fungus enzymes break down the pectin in fruit, the fruit gets soft and mushy.
Pectin is a thickener in many products. If there is sufficient sugar in the mixture, pectin forms a firm gel.
Jams and jellies are thickened with pectin. Pectin binds water, and thus keeps products from drying out. It stabilizes emulsions.
Pectin combines with the calcium and whey proteins of milk, stabilizing foams and gels made with cream or milk.
Pectin is not digested, and is considered a beneficial dietary fiber.