pectin

Etymology

From French pectine, coined in the 1830s by Henri Braconnot, from acide pectique "pectic acid", from Ancient Greek πηκτικός (pēktikós, “curdling”), from πηκτός (pēktós, “curdled”), from πήγνυμι (pḗgnumi, “stiffen”).

noun

1. (biochemistry) A polysaccharide extracted from the cell walls of plants, especially of fruits; under acidic conditions it forms a gel. It is often used in processed foods, especially jellies and jams where it causes thickening (setting).
   Apple is rich in pectin and so is often added to other fruits when making jam so it will set.