Nutrition & Microwaves

The time saving convenience and energy efficiency of cooking with a microwave is undeniable but you may be concerned about the safety of microwaves and their effect on food. Cooking with a microwave depends on understanding the limitations as well as the nutritional benefits of this type of cooking.

How Microwaves Work

Microwave ovens use electromagnetic energy to cook. These waves travel at the speed of light to produce micro wavelength radiation, which interacts with the molecules in the food. The wave energy changes from positive and negative with each cycle, referred to as polarity. Water molecules in food, which are polar, energize and cause their molecular neighbors to vibrate.

Vitamins and Antioxidants

Many vegetables are robbed of some of their nutritional value when cooked in water, which leaches out the vitamins. Foods cooked in a microwave oven retain more vitamins and minerals because microwave ovens cook quickly with little or no water, says United States Food and Drug Administration. Changes in the antioxidant activity of phenolics, ascorbic acid and carotenoids in broccoli from conventional verses microwave cooking was investigated in a study conducted at Shinshu University, Japan in 2003. Conclusions, published in Food Chemistry, found that antioxidants in broccoli were lost heavily during cooking but less with microwave, which retained 65 percent of phenolics antioxidant properties, as compared to conventional cooking methods at 34 percent.

Glucosinolate

Boiling vegetables such as broccoli, Brussels sprouts, cauliflower and cabbage, causes a loss of glucosinolate, the sulfur-containing compound that helps fight cancer. Since cooking in a microwave uses little or no water, the steaming process maintains nutritional content. Researchers at the University of Warwick found that cooking vegetables in the microwave for three minutes produced no significant loss of these nutrients, compared to boiling for 30 minutes, which caused a 77 percent loss of glucosinolate in broccoli, a 58 percent loss in Brussel sprouts, a 75 percent loss in caulliflower and a 65 percent loss in cabbage.

Protein

Meat cooked in a microwave retains a higher quality of protein than when cooked in a convention oven as far less oxidation occurs, according to the Commonwealth Scientific and Industrial Research Organization. Visible evidence of gentler heating is the lack of browning of meat.

Reheating and Defrosting

Using a microwave to reheat food quickly retains more nutrients than keeping food hot for extended periods of time. This is significant in cafeterias, hospitals and institutions where food needs to be served hot for several hours. When using the microwave to defrost foods, finish cooking the food immediately. Food may begin to cook during the defrost cycle, providing enough warmth for bacteria to start multiplying.