Anyone who’s tried baking a cake or cooking a hunk of beef in a microwave oven is familiar with the usual results: The cake fails to brown or develop any pleasing caramel flavor, and the meat tastes more steamed than roasted.
While praising the speed and ease of microwaving-the ovens are now in 90 percent of U.S. households-microwave experts caution consumers that the popular device isn’t meant to do everything.
Cookbook author Barbara Kafka wouldn’t dream of trying to roast a chicken in a microwave oven. But she insists that fish, vegetables and even risotto often turn out better when prepared in one.
“People cook many things in a microwave that don’t belong there, so they don’t get good results,” says Kafka, who wrote “The Microwave Gourmet” and “The Microwave Gourmet Healthstyle Cookbook.”
Recently, a pair of researchers offered another explanation for why the microwave’s high-speed cooking sometimes yields unflattering flavors.
They blame it on chemistry.
Researchers at the University of California at Davis report that food cooked to the same degree of doneness in a microwave and a conventional oven, undergoes vastly different chemical changes.
Takayuki Shibamoto, a professor of environmental toxicology, and Helen Yeo, now a post-doctoral research fellow at the University of California at Berkeley, discovered that cakes, beef and vegetables prepared in a traditional way were significantly higher in compounds consumers find desirable.
Four studies showed that compounds called furans, pyrazines and thiazoles-which lend caramel-like, nutty and meaty flavors to ingredients-were formed in greater amounts in food produced by thermal heating.
Here’s why: A conventional oven gives off dry heat and cooks from the surface down, allowing for flavor-enhancing browning and crisping.
Such attributes spring from a series of chemical reactions that occur between sugar molecules (carbohydrates) and amino acids (protein) subjected to high heat over a period of time.
On the other hand, food prepared in a microwave oven delivered higher levels of oxazoles, thiophenes and pyrroles-compounds that produce fishy, burnt and pungent tastes.
Microwaved beef was more pungent and sour, and microwaved cabbage had more sulfurous and burned components than when either was boiled, for example. Microwaved cake produced a “green vegetable” flavor rather than butter or caramel notes.
The short cooking time and relatively low temperature achieved during microwave irradiation inhibits the chemical reactions that render conventionally cooked food so appealing, the researchers concluded.
“The microwave oven strikes me as a blunt instrument,” fine for some things, indispensable for others, says kitchen scientist Harold McGee, author of “The Curious Cook.”
Except for fish, he’s never had luck microwaving any kind of meat, and finds some vegetables (carrots) do better than others (green beans, which toughen, he says).
Like most consumers, McGee uses the device mostly to reheat food, although he’s developed a way to sterilize eggs for “absolutely safe” bearnaise, hollandaise and mayonnaise.
The microwave heats small amounts of food (i.e., yolks) rapidly and from all sides, the author says, and “the food won’t exceed the boiling point unless it begins to dry out.”
For her part, Kafka says she’s never experienced off-flavors cooking fruits or vegetables in a microwave oven and has achieved great success cooking small cuts of meat (like filet mignon in broth) in the appliance. Further, cake is something she wouldn’t even consider making in a microwave oven, she says.
Americans own about 120 million microwave ovens, but we mainly use them to reheat leftovers, pop popcorn and cook frozen meals, says a recent study by Campbell Soup.
Robert Schiffman of Schiffman Associates, a microwave consulting firm in New York City, says that fewer than 30 percent of microwave oven owners use them to cook meat and fish, and fewer than 15 percent bake cakes, cookies or pastries in them.
That bothers CiCi Williamson, author of three cookbooks on the subject. She calls the microwave oven “the fax machine of the kitchen” and enthusiastically sings the praises of an appliance that can cook an artichoke in 4 minutes and dry herbs in seconds-and one that doesn’t require the addition of fat to food prepared in it.
In all, it’s generally a healthier way to cook, Williamson says.
Research conducted by Gertrude Armbruster, a nutritional scientist at Cornell University, showed that when certain foods are microwaved, they remain more nutritious than when they are boiled, baked, grilled or even steamed on conventional stove tops and ovens.
Armbruster studied vitamin C, the most heat-sensitive vitamin, and found that because the microwave cooking time was shorter, and because there was no need to use extra water to prevent burning, the final level of the nutrient was higher with microwave cooking than with methods requiring more water and longer heating.
Vegetables microwaved in a teaspoon of water a serving retained up to 100 percent of their vitamin content, while boiled vegetables retained only 40 to 60 percent. The same would hold true for other water-soluble vitamins, like B vitamins, Armbruster said.
And because electromagnetic waves don’t brown food, meat cooked in a microwave oven contains higher levels of protein than baked, broiled or grilled meats, she said.
