The microwave oven has become an essential kitchen appliance in every household. Besides heating food, people also use it to steam custards, stir-fry dishes, and even make soups. It is convenient and avoids the hassle of smoke and fumes, making it particularly popular with housewives. But is microwave cooking better or worse compared to conventional methods like frying, boiling, and stewing?
Microwave cooking is a new method that heats food molecules rapidly. What it actually heats are mainly the water molecules in the food, so it is suitable for various moisture-rich foods.
Microwave cooking can better preserve vitamins. Due to its higher efficiency and shorter cooking time, with less water loss, the degradation of various vitamins when food is cooked or pasteurized is lower than with stir-frying and significantly lower than with boiling.
Microwave cooking can keep vegetables fresh. A study using green asparagus illustrates this point. To make canned asparagus, researchers designed several sterilization systems: a microwave circulating water heating system, a high-pressure water heating system, and a conventional steam heating system. The final results showed that the antioxidant activity from sterilization with the microwave system was even higher than the other two methods. Microwave cooking preserves the fresh green color of vegetables with less loss of chlorophyll. For example, after microwave cooking, bitter vegetables lost only 8.2% of their chlorophyll, whereas after blanching, the loss reached 46.9%.
Microwaves can also reduce carcinogens produced during heating. Research has found that microwave heating is short in duration and easy to control, making it less likely to cause uneven or excessive heating. This can reduce the carcinogens produced from high-temperature cooking of food, such as heterocyclic amines formed from overheated proteins and acrylamide produced from overheated starchy foods.
However, every advantage has its disadvantage. Microwave cooking may reduce the content of beneficial fatty acids in meat. In a recent research report, the changes in fatty acids in beef after heating were measured. Some samples were microwaved, while others were conventionally steamed, until the internal temperatures were the same. The results showed that compared to steaming, microwave heating led to a significant decrease in the proportion of omega-3. In contrast, lower-temperature steaming has a smaller impact on unsaturated fatty acids and may even slightly increase the content of polyunsaturated fatty acids.
Therefore, microwave cooking is more suitable for high-moisture, low-fat foods like soups and vegetables. For foods rich in omega-3, such as fish, duck, seafood, and egg yolks, it is better to choose traditional steaming methods.