Because microwave ovens cook so fast, they tend to destroy fewer vitamins than conventional cooking methods. We’ve known for ‘some time that one potential problem with this type of cooking, however, is that it may heat foods unevenly and leave some parts undercooked, thus allowing bacteria and other microorganisms to survive. This is easily remedied by rotating foods, for instance, and checking the internal temperature. But, because of the unique way microwaves cook food, and the speed with which they do so, new concerns have arisen about microbes that may survive on the surface of food.
Most people know that they must cook pork well enough throughout to prevent trichinosis, but this is hardly the only food that can be contained with disease-causing microbes. For example, Salmonella in undercooked poultry has been responsible for an increasing.
number of infections. A study of Georgia Southern College in Statesboro compared Salmonella inoculated chickens that were either cooked conventionally or microwaved.
Those cooked conventionally contained no live bacteria, but eight out of nine microwaved chickens did. And several other studies have shown that hot dogs, hamburgers, and tomato soup, all contaminated with bacteria, had higher levels of surviving organisms after microwaving than after conventional cooking.
Microwaves cook food by vibrating water molecules. Much of the moisture near the outside of the food evaporates, leaving the surface cooler than the inside. The air around the food remains cool too unlike the searing air in a conventional oven so that organisms present on the surface have a greater chance of serving. Thus while the center of a hamburger may be steaming hot, the edge may remain cool and contaminated.
The ways around the problem are simple enough: * Wrap food in plastic made to be used in microwave ovens, or cover it with glass or ceramic. The trapped steam will help decrease evaporation and will heat the surface. Be sure to prick a hole in the plastic wrap to vent steam. * Allow microwaved food to stand covered after the cooking time is over. Heat concentrated on the inside will radiate outward through the food, cooking the exterior and equalizing the temperature throughout. Food will taste better this way, too, since it will be consistently hot. * Thaw meats before cooking in a microwave oven; most models have defrost settings for this purpose. Ice crystals in frozen foods are not heated well by microwaves and can leave cold spots * If you’re used to conventional cooking, remember that the more food you’re microwaving the longer it will take. For example, four baked potatoes will take much longer than two.
Article extracted from this publication >> May 26, 1989
