As a dietary fiber, apple pectin is helpful in maintaining good digestive health. Fruits rich in apple pectin include the peach, apple, currant, and plum. Protopectin, present in unripe fruits, is converted to pectin as the fruit ripens. Pectin forms a colloidal solution in water and gels on cooling. When fruits are cooked with the correct amount of sugar, and when the acidity is optimum and the amount of pectin present is sufficient, jams and jellies can be made. In overripe fruits, the pectin becomes pectic acid, which does not form jelly with sugar solutions.