Everyone has heard about food preservatives, but how do they work? Chemical & Engineering News, in the Nov. 11 issue, explains what these useful chemicals can do to keep food safe and palatable. Chemical preservatives can't take the place of stronger preservation methods, like commercial sterilization, which kills most bacteria and enzymes, but they can be used effectively to retard spoiling and to stop the growth of harmful microorganisms.
Chemical & Engineering News is a weekly newsmagazine published by the American Chemical Society, the world's largest scientific society.
Preservatives can be grouped into three general types: antimicrobials that block growth of bacteria, molds or yeasts; antioxidants that slow oxidation of fats and lipids that leads to rancidity, and a third type that fights enzymes that promote the natural ripening that occurs after fruits or vegetables are picked.
Sulfur dioxide works in all three areas and is part of a larger group called sulfites, compounds found in numerous foods. A small percentage of people are allergic to sulfites, but the FDA says the preservative is safe for the majority. Some vinegars, fruit juices and dried fruits contain sulfites.
Sulfites block the growth of microbes by interrupting the normal functioning of their cells, according to Hassan Gourama, Ph.D., associate professor of food science at Pennsylvania State University.
Propionates are antimicrobials that help keep bakery products fresh. Propionic acid occurs naturally in apples, strawberries, grains and cheese. It works against bread molds and spores of a bacterium that leads to a condition called "rope" that makes bread inedible. Benzoates, another weak antimicrobial, fight fungi, working best in areas at a
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Contact: Michael Bernstein
m_bernstein@acs.org
202-872-6042
American Chemical Society
12-Nov-2002