Microwave Versus Conventional Cookery

Microwave Versus Conventional Cookery of Popcorn and Other Foods^*

The microwave oven, often erroneously referred to as a microwave, is a controversial device. Some are concerned about the leakage of microwave radiation. Others wonder if “microwaving” develops harmful substances in food. Still others use it all the time and love it and are as happy as clams at high tide.

Microwave-radiation leakage would be expected to be insignificant, considering the pains manufacturers of these ovens take to insulate their products. However, the danger of electromagnetic radiation from any device using alternating current at high energy levels is suspected by some scientists to be harmful. Therefore, to play it safe, I stay at least a few feet away from my microwave oven and any other high-wattage electrical equipment while they are operating.

The way microwave radiation heats food is by jiggling its molecules, thereby increasing their thermal energy. Heating over a flame does essentially the same thing. However, microwaves penetrate into the interior of the food, whereas in conventional cooking, heat is transferred to the interior only by thermal conduction through the food. This feature of microwave cooking is advantageous in one respect and worrisome in another.

In heating water, there is no concern with either method. Molecules of water cannot be altered by either method. Therefore, foods that are primarily water are probably not deleteriously affected by microwave heating and can be cooked faster than with conventional heating. However, for foods containing fats, I am concerned that microwave radiation may unequally penetrate to some parts, heating them to inordinately high temperatures. This unequal heating may result in local free-radical formation. Of course, conventional heating also produces free radicals.

Therefore, for any food containing fat—especially vegetable fat—I regard cooking by microwaving to be similar to frying, which I avoid.

These days, making popcorn in a microwave oven is quite popular. Unfortunately, some of the plastic coating of the paper bag containing the popcorn evidently vaporizes and then migrates into the food. Additionally, most microwave popcorn contains partially hydrogenated vegetable oil and artificial flavor, which are harmful and also create an objectionable odor in the room. Even if you use an ordinary paper bag and natural popcorn, the unequal heating effect and absence of motion causes some of the popped kernels to be subjected to objectionably high temperatures, thereby producing free radicals.

A hot-air popper is definitely the best. The kernels are kept moving and immediately jump away from the source of heat when popped.

^*From Robert Chuckrow, The Intelligent Dieter’s Guide, Rising Mist Publications, Briarcliff Manor, NY, 1997.