Pectin is a soluble, sticky polysaccharide that acts as a cementing material between the cell walls of all plant tissues. Pectin is the methylated ester of between 300 to 1000 units of polygalacturonic acid, shown on the right. Pectin is used in the food industry as a gelling agent for foods such as jellies, jams and fruit preserves. The Degree of Esterification (DE) affects the gelling properties of pectin. The structure shown above has three methyl ester forms (-COOCH3) for every two carboxyl groups (-COOH), hence it is has a 60% degree of esterification.