Apple pectin is the soluble fibre fraction of the apple fruit - protopectin, present in unripe fruits, is converted to pectin as the fruit ripens. The apple provides the most pectin of all fruits, with the Jonagold variety containing the highest levels.
Pectin comes in liquid or dried form from the solid fruit residue, with 10-20% pectin in the dried mass. The pectin is extracted from the dried residue at pH 1.5-3, and at temperatures ranging from 60-100°C.
Apple pectin has been shown to increase the excretion of lipids, cholesterol and bile acids, and reduce cholesterol levels. It operates by binding with bile acids, thereby decreasing cholesterol and fat absorption, and it therefore also helps prevent gallstones from forming.
As a dietary fibre, apple pectin is helpful in maintaining good digestive health, and may lessen the severity of diabetes, as it has been suggested that fibre-depleted diets actually help cause diabetes mellitus.
The pectin helps to maintain intestinal balance by cleansing the intestinal tract with its soluble and insoluble fibres. It tends to increase acidity in the large intestines, and is advocated for those suffering from ulcers or colitis. Pectin also may modify intestinal bacterial enzyme activity in favor of a reduction of toxic breakdown products in the gut.
Preliminary evidence suggests a positive relationship between lung function and consumption of five or more apples per week, although the reason for this is unknown - it has been proposed that the antioxidant flavonoid quercetin may play a major role.