Food Chemistry Tip Sheet March 1998

EMBARGOED FOR RELEASE: Sat., Feb. 28

For further information, contact:
Jim Bohning
202-872-6041
[email protected]

FOOD CHEMISTRY TIP SHEET _ March 1998

The following research articles will appear on February 28 in the Web edition of the Journal of Agricultural and Food Chemistry, a peer-reviewed journal published by the American Chemical Society, the world's largest scientific society.

MICROWAVE COOKING REDUCES PCB LEVELS IN ATLANTIC BLUEFISH Atlantic bluefish, a popular species caught by sports fishermen on the North and Mid-Atlantic coasts of the United States, have feeding habits and a long lifespan that make them quite susceptible to accumulating polychlorinated biphenyls (PCBs), which are potential health hazards. Now it appears that certain cooking techniques can dramatically reduce the amount of PCBs -- and therefore your exposure to them -- in the edible parts of bluefish. A study conducted at the University of Massachusetts showed that the most effective methods were smoking and microwaving, resulting in a 65 and 60 percent loss respectively of PCBs. Charbroiling with the skin off reduced PCBs by 46 percent, convection oven cooking by 39 percent, charbroiling with the skin on by 37 percent, and pan frying by 27 percent. While PCB levels in raw bluefish in the mid-1980s exceeded FDA recommendations, the study shows that a decade later, PCB levels are now below the FDA tolerance level. This significant!

change may be due to increased PCB regulatory efforts in the U.S. and Canada.

TAKING A COLD LOOK AT THE CHEMISTRY OF STALE BEER Consumers usually consume beer cold, and cold storage temperatures contribute to a longer shelf life and a better taste. But when stored above room temperature, the ethanol in the beer oxidizes to form a compound called acetaldehyde. In this study conducted at the University of California, Davis, the acetaldehyde formed in warm beer was used as a chemical marker to determine how much the flavor was reduced. Although more than 900 flavor compounds have been identified in beer, the acetaldehyde content is among factors most closely linked to a stale flavor. The California researchers found that the acetaldehyde increased 873 percent in beer samples stored 90 days at 122 degrees F. But a compound named GIV that is isolated from young green barley leaves was found to act as an antioxidant when added to beer and reduced the acetaldehyde by 60 percent in beer stored for 10 days at the same elevated temperature. Beer is often subjected to elevated temperatures during shipment, and the findings could be particularly useful especially in underdeveloped countries where refrigeration resources are scarce. Because GIV itself is tasteless and inhibits acetaldehyde formation better than other known antioxidants such as vitamin E, the researchers recommend its use in preserving beer flavor.

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