Pectin

OVERVIEW

Pectin (PEK-tin) is a mixture, not a compound. Mixtures differ from compounds in a number of important ways. The parts making up a mixture are not chemically combined with each other, as they are in a compound. Also, mixtures have no definite composition, but consist of varying amounts of the substances from which they are formed.

Chemically, pectin is a polysaccharide, a very large molecule made of many thousands of monosaccharide units joined to each other in long, complex chains. Monosaccharides are simple sugars. The most familiar monosaccharide is probably glucose, the sugar from which the human body obtains the energy it needs to grow and stay healthy. The monosaccharides in pectin are different from and more complex than glucose.

KEY FACTS

FORMULA:

Not applicable

ELEMENTS:

Carbon, hydrogen, oxygen, and other elements

COMPOUND TYPE:

Not applicable

STATE:

Solid

MOLECULAR WEIGHT:

Varies widely: 20,000 to 400,000 g/mol

MELTING POINT:

Not applicable

BOILING POINT:

Not applicable

SOLUBILITY:

Soluble in water; insoluble in organic solvents

Pectin occurs naturally in many fruits and vegetables. It is most abundant in citrus fruits such as lemons, oranges, and grapefruits, which may consist of up to 30 percent pectin. In pure form it is a yellowish-white powder with virtually no odor and a slightly gummy taste. When dissolved in water, it forms a thick, jelly-like mass. This property explains one of its primary purposes: the jelling of fruits when they are made into jams and jellies.

HOW IT IS MADE

Pectin is made naturally in ripening fruit. It is obtained commercially by treating the raw material (citrus peel or apple pomace) with hot, acidified water. (Apple pomace is the residue remaining after pressing of apples.) The pectin in the peel or apple pomace dissolves in the hot water and is then purified by repeated filtrations. It is extracted from the water solution by adding alcohol or an aluminum salt to the solution, causing the pectin to precipitate out of solution. The precipitate is then dried and ground into a powder.

Additional steps are sometimes carried out to convert the pectin produced by this method, called high ester pectin, to a form that is more soluble: low ester pectin. To achieve this change, high ester pectin is treated with either acids or alkalis, washed, and purified.

COMMON USES AND POTENTIAL HAZARDS

Pectin is used primarily as a jelling agent in the manufacture of jams and jellies. It also has a number of other applications as a food additive. For example, it is added to some yogurts to provide the consistency that allows the yogurt to hold its shape and still be capable of being stirred. It is added to concentrated fruit drinks to keep the solid and liquid components of the drink in suspension with each other. It is also an ingredient in fruit and milk desserts, added to ensure that the final product has the proper consistency and stability.

Pectin is also used as an additive in pharmaceutical and cosmetic preparations. It acts as an emulsifying agent, to stabilize the product, or to give it the proper consistency. In combination with an antibiotic, pectin has also been used as an anti-diarrheal agent. Some studies have shown that daily doses of pectin may have a small but significant lowering effect on cholesterol levels.

The U.S. Food and Drug Administration has classified pectin as an approved food additive. It is considered safe for human consumption when used in normal amounts as a food additive. It may cause some digestive problems for people with allergies to citrus fruits. Some studies suggest that pectin may also inhibit the absorption of minerals such as zinc, copper, iron, and calcium, although this effect is not serious enough to prevent its use as a food additive.

Interesting Facts

• The role of pectin in the formation of jams and jellies from fruits was first recognized in the 1820s.
• The first commercial manufacture of pectin took place in Germany in 1908. Producers of apple juice found that they could use apple pomace, previously a waste product, to make a useful product that could be sold, pectin.
• The first recipes for the use of pectin to make jams and jellies date to the first century when the Roman writer Marcus Gavius Apicius wrote a recipe book "Of Culinary Methods.';
• American inventor Paul Welch was granted a patent in 1917 for the production of grape jam, using pectin. Welch called his product Grapelade and sold his entire production to the U.S. Army. The Army sent the Grapelade to troops serving in Europe in World War I (1914–1918). After the war, returning troops demanded more Grapelade, making it a popular consumer item in the United States.

Words to Know

EMULSION

A temporary mixture of two liquids that normally do not dissolve in each other.

POLYSACCHARIDE

A very large molecule made of many thousands of simple sugar molecules joined to each other in long, complex chains.

FOR FURTHER INFORMATION

"Genu® Pectin." CP Kelco. http://www.cpkelco.com/food/pectin.html (accessed on December 22, 2005).

Knox, J. Paul, and Graham B. Seymour, eds. Pectins and Their Manipulation. Boca Raton, FL: CFC Press, June 2002.

"Pectin." http://www.cfs.purdue.edu/class/f&n630/Virt_Class_2/pectin.htm (accessed on December 22, 2005).

"Pectin." PDRHealth. http://www.pdrhealth.com/drug_info/nmdrugprofiles/nutsupdrugs/pec_0198.shtml (accessed on December 22, 2005).

See AlsoGelatin

pectin Plant tissues contain hemicelluloses (chemically polymers of galacturonic acid) known as protopectins which cement the cell walls together. As fruit ripens, there is maximum protopectin present; thereafter it breaks down to pectin, pectinic acid, and, finally, pectic acid, and the fruit softens as the adhesive between the cells breaks down.

Pectin is the setting agent in jam; it forms a gel with sugar under acid conditions. Soft fruits, such as strawberry, raspberry, and cherry, are low in pectin; plums, apples, and oranges are rich. Apple pulp and orange pith are the commercial sources of pectin. Added to jams, confectionery, chocolate, and ice cream as an emulsifier and stabilizer instead of agar; used in making jellies, and as an anti‐staling agent in cakes. Included in non‐starch polysaccharides.

pec·tin / ˈpektin/ • n. a soluble gelatinous polysaccharide that is present in ripe fruits and is extracted for use as a setting agent in jams and jellies.DERIVATIVES: pec·tic / ˈpektik/ adj.

pectin One of a group of homopolysac charides that contain a variety of monosaccharides, but are especially rich in galacturonic acid. They form a kind of cement, so contributing to the structure of plant cell walls, being particularly abundant in young primary walls and fruits.

pectin Water-soluble polysaccharide found in the cell walls and intercellular tissue of certain ripe fruits or vegetables. When fruit is cooked, it yields a gel that is the basis of jellies and jams.