1. Make good use of iron pans
Remember to cook acidic foods like tomatoes, apples, and lemons in an iron pan. A study by Texas Tech University found that heating such acidic foods in an iron or stainless steel skillet can increase the amount of absorbable iron by more than 20 times.
The U.S. magazine *Prevention* also suggests that cooking iron-rich foods with acidic ingredients can increase iron absorption by 10 times. For example, adding tomato sauce when cooking beans can help absorb the iron from the beans.
2. Add garlic later for better cancer prevention
Garlic is an indispensable ingredient in the kitchen, but did you know that high temperatures destroy allicin, the most important enzyme in garlic for cancer prevention and immune enhancement? Researchers from Pennsylvania State University and the U.S. National Cancer Institute suggest that after chopping garlic, don't rush to put it in the pan. Let the crushed garlic sit for 10-15 minutes before cooking. This way, the destruction of nutrients due to heating can be reduced.
3. For broccoli, microwaving is better than boiling
How do you usually cook broccoli? Whatever you do, don't boil it. A study published in the *Journal of Food Science* pointed out that boiling or steaming can cause a 34% and 22% loss of vitamin C in broccoli, respectively. In contrast, microwaving can retain over 90% of the vitamin C, which has anti-cancer properties!
Vegetables are high in potassium, which is more likely to be lost when boiled. Additionally, if you add more salt during cooking, potassium will also be lost. (In fact, cooking vegetables with a lot of water causes a significant loss of nutrients.) If ingredients are rich in B vitamins (e.g., whole grains) or vitamin C (e.g., fruits and vegetables), they are more sensitive to light and heat. Therefore, the longer the cooking time, the more nutrients are destroyed; repeated washing and reheating also lead to greater nutrient loss. So, if you want to add fruit to a dish for extra flavor, you should add it just before turning off the heat to reduce cooking time and preserve more nutrients.
4. To fight cancer, boil carrots whole before cutting
A new study in the UK found that boiling carrots whole before cutting increases the anti-cancer compound 'falcarinol' by a quarter compared to cutting them first. The scholar from Newcastle University, who led the study, pointed out that cutting carrots before cooking increases the surface area for nutrients to leach into the water. Conversely, boiling them whole first locks in the nutrients.
And they taste better too. The study also found that 80% of participants believed that carrots boiled whole tasted better than those cut first. This is because when boiled whole, the concentration of natural sugars that give carrots their unique sweetness is higher than when they are cut first.
5. Cooked tomatoes are better for your heart
Lycopene-rich tomatoes become easier for the human body to absorb when cooked. A study by Cornell University found that no matter the cooking method, tomatoes cooked for 30 minutes released significantly more lycopene than raw tomatoes. Plant pigments like lycopene and carotene are trapped in the plant cell walls. Cooking them with oil helps release these nutrients, making them more easily absorbed by the body.
6. For more calcium, add some lemon juice
Next time you cook chicken soup at home, remember to add some lemon juice, vinegar, or tomatoes. Harvard University research indicates that doing so can increase the calcium content in the broth by 64%.
7. Don't rush to peel
Are you in the habit of peeling eggplants, apples, and potatoes? If so, you're throwing away nutrients. The peel itself is a natural barrier that prevents nutrient loss, and many vitamins and minerals are found in or just under the skin.
As long as the food's peel is digestible after cooking, eat as much of it as you can. So the next time you cook potatoes, first rinse off the surface dirt and pathogens with running water and scrub them clean. Then you can cook them by steaming, roasting, or microwaving.
8. Peanut skins prevent stomach bleeding
Additionally, in Traditional Chinese Medicine, the skins of some foods are considered a potent remedy. Clinically, the most valuable medicinal part of a peanut is its skin (commonly called the red skin).
When eating peanuts with alcohol, people often rub off the skins with their fingers, not realizing that peanut skin is an excellent hemostatic agent. Alcohol causes blood vessels to dilate. If the gastric mucosa and stomach wall are weak, continued dilation after drinking can easily lead to stomach bleeding. The anticoagulant effect of peanut skin can prevent this.
9. Winter melon and watermelon skins are diuretic and anti-inflammatory
When making winter melon soup, don't peel it. Just scrub the skin clean and cook it with the flesh for a better diuretic and antipyretic effect. Besides winter melon, it is said in traditional wisdom that the cooling properties of watermelon are in its skin, which is where the medicinal value lies. Zhang Butao suggests that if you want to use watermelon as a diuretic, it's best to wash the skin clean, keep the white flesh just under the skin, and cook them together in a soup. After it cools, drinking it can have anti-inflammatory, pus-discharging, and diuretic effects.
10. Stir-frying meat quickly retains more vitamins than stewing
The length of cooking time also changes the structure of ingredients. Yang Que Lian points out that for example, if meat is stir-fried for too long, its texture becomes tough, which is not good for chewing and digestion. While long stewing can make the meat tender, it also causes significant loss of B vitamins, which are abundant in meat.
Furthermore, when meat is cooked by braising or stewing, nutrients like potassium leach into the broth. Unless you drink the broth too, its nutritional value is diminished. (But drinking the broth can also lead to excessive intake of salt and fat.) It's better to cut the meat into shreds or small pieces to allow for quick, short stir-frying, which helps retain more nutrients.