- noun a sticky mixture of various polysaccharides found in plant cell walls
- A natural hemicellulosic carbohydrate gelling agent which in acid conditions (less than 3.46 pH) causes jam and marmalades to set. If the acidity is too low, less than 3.2 pH, then the jelly will weep, boiling also reduces the gelling power. citrus fruits, apples, currants and some plums are rich in pectin and acids. Other fruits require added pectin and acid to make a satisfactory jam.
- noun a substance in fruit which helps jam to set