How does microwaving and freezing food affect its nutritional content?
Most of us try to eat healthily every day, however what many people don’t know is that the nutritional value of the fruits and vegetables we usually eat has already been affected before reaching our plates. Learning about food handling and cooking procedures will allow us to take advantage of the nutrition in food much more effectively.
It seems simple enough to cook food in the microwave or to use it to thaw frozen strawberries, but it’s important to know what happens to food during this process. When the first microwave oven was sold in 1946, people were very cautious about this radar technology inspired by the Second World War. At that time, microwaves were as heavy as a refrigerator and the price relatively high. Owning a microwave oven was a symbol of being upper class. Today, almost every American family has a microwave oven, but the fear over them has never been completely eliminated and many people still believe it can seriously damage the nutritional content of food.
Harvard Medical School noted that nutrients break down under the influence of heat, whether that’s microwave heating or stove/oven heating. As for vegetables, if immersed in water during the cooking process, some nutrition is lost. These nutrients seep into the boiled cooking water, which should be utilized as sauces and soups in order to retain the nutrients.
Microwave sceptics also claim that microwaves will make nutrients “unhealthy” and make it harder to measure calories in protein, carbohydrate and fat. Indeed, the microwave can slightly reduce the nutritional value of protein in certain foods, such as chicken, but it hardly has an impact on the overall nutrition of the food.
However the rumour that freezing destroys the nutritional value of food is true, as the degradation of nutrients in fruits and vegetables does occur in the procurement process and when they are placed in the refrigerator. To prevent this from happening, people should buy seasonal fruits and vegetables. For example, you can buy frozen strawberries in June when they are ripe or buy fresh strawberries and freeze them by yourself. The nutritional content of seasonal fruits and vegetables is rich, and it is the best time for consumption.
For eating frozen food there is a rule of thumb, which is to try to heat frozen food thorough steam or microwave rather than boiling, thus avoiding the loss of water-soluble nutrients. In addition, we also need to take into account that some of the nutritional content of food was lost before freezing - that is, put food in water when the water is boiled. This kind of food is not completely cooked due to the short time. This step is for frozen vegetables such as broccoli, leafy green vegetables, green beans, okra and asparagus. In fact, it suppresses the activity of enzymes which can cause decay, helping to maintain the quality of food and nutrients during the freezing process for weeks or even months. It reduces about 25% of vitamin C, folic acid and 10% of vitamin B1 in food, but these values also vary widely due to different method of operating.
Another controversy involving food handling is that of dried fruit and fresh fruit. People eat fruit not only because it is sweet, but mainly for its antioxidant and high fibre content. Dried fruit is fresh fruit without moisture, but can be kept for a longer time. If fruit is cook and dried, it can contain all the vitamins and minerals you find in fresh fruits, not to mention the cooking process kills microorganisms. It is not important whether you eat dried apricots or fresh apricots as a snack, but we should give priority to the one with the highest nutritional content. Some fruit is more vulnerable to pesticides than others, perhaps you have drunken a cup of chemical cocktail without knowing, thinking you were eating healthy. According to a report from US President cancer research group, fruits and vegetables like celery, peaches, strawberries, apples, spinach, cabbage, kale, cherries, potatoes, imported grapes and lettuce have the highest amount of pesticide.
Fortunately, we still have a long list of safe fruits and vegetables to eat, including onions, avocado, sweet corn, pineapple, mango, sweet peas, asparagus, kiwi, eggplant, melon, watermelon, grapefruit and sweet potatoes. Their skin layer can be seen as an important protector, making them safer to eat than other fruits and vegetables. Frozen, boiled and microwave-heating food has both advantages and disadvantages, but it is the biggest loss of nutritional supplement throughout the preparation process.
References:
Samantha Olson
Healthy Eating: Learn Myths and Facts About Microwaving, Freezing, And Killing Your Food's Nutrition
medicaldaily.com
By 张萌
