Did you know? Even if you always choose nutritious ingredients, if the cooking method is improper, the nutrients can sneak away. The Life Times has interviewed authoritative nutrition experts to help you uncover the "mysterious thieves" that steal nutrients.
Fruits and Vegetables are All Peeled
Many people are afraid of pesticide residues on the surface of vegetables and usually peel them before cooking, such as eggplant skin, zucchini skin, radish skin, etc.
In fact, the skins of vegetables contain a variety of nutrients such as dietary fiber, vitamins, chlorophyll, minerals, and antioxidants. Eating them after peeling actually loses many nutrients.
To reduce pesticide residues, it's best to scrub fruits and vegetables vigorously under the tap first. For fruits and vegetables with a "firm" exterior, a small brush can also be used for washing. After you feel they are clean, rinse them with water for another 15-20 seconds before eating. Soaking in tap water can also remove some pesticide residues, but don't soak for too long; about 10 minutes is appropriate.
Cutting Vegetables Before Washing
Many people, for convenience, cut the vegetables first and then wash them together. However, this causes water-soluble vitamins like B vitamins and vitamin C, as well as some minerals, to dissolve into the water, resulting in loss.
For example, many people soak shredded potatoes and eggplant directly in water after cutting. While this prevents discoloration, a large amount of nutrients is also silently lost. Moreover, rinsing vegetables after cutting allows pesticide residues and dirt on the surface to easily enter the cut surfaces.
Therefore, the correct method is to wash the vegetables thoroughly first, and try to drain the moisture before cutting. Additionally, when washing rice before steaming, do not rub it repeatedly, otherwise a large amount of B vitamins will also be lost.
Cutting Too Finely
As the saying goes, "food is never too refined," but from a nutritional perspective, vegetables are not better the finer they are chopped. Because the smaller the pieces, the larger the surface area, and the greater the contact with air and the hot pan, the more severe the nutrient loss.
Some nutrients will also be lost along with the vegetable juices. Moreover, some people are used to pre-cutting ingredients for preparation, but this can cause easily oxidized vitamins like vitamin C, vitamin E, and B vitamins to be lost. Therefore, it is best to cut vegetables just before stir-frying and eat them right after cooking.
Blanching for Too Long
Some vegetables need to be blanched in boiling water after being cut, which can remove oxalic acid and even residual pesticides, and synchronize the ripeness of all ingredients. However, if there is too little water in the pot or the heat is too low, the blanching time will be extended, causing a significant loss of nutrients in the vegetables.
The solution is to use as much water as possible when blanching, turn the heat to maximum, and shorten the blanching time. Generally, the vegetables can be scooped out as soon as their color changes slightly. You can also add a few drops of oil to the water to "seal" the cut surfaces of the vegetables and prevent oxidative loss.
Randomly Using Alkali to Marinate Meat
Many people like to use alkaline substances such as baking soda and meat tenderizer to marinate meat to make it more tender and smooth. However, these alkaline substances can cause protein denaturation, making it difficult for the body to absorb; when fat meets alkali, a saponification reaction occurs, which not only makes it lose its value but also produces an unpleasant odor; moreover, a large amount of B vitamins in the meat will be completely lost.
Usually, when marinating meat, you can mix the meat slices with salt, pepper, Shaoxing wine, egg white, and starch, then pan-fry them at an appropriate temperature. This can well preserve the nutrients and also tastes good.
Deep-frying Ingredients First
When making dishes like Di San Xian (three fresh ingredients stir-fry) or dry-fried green beans, many people like to first pass the ingredients through hot oil, scoop them out, and then stir-fry. This makes the dishes look bright and smell fragrant.
However, this cooking method not only destroys the original nutrients in the dishes, but also loses the originally rich vitamins. The meat that has been deep-fried is also difficult to digest and can lead to excessive intake of oil.
Therefore, when cooking at home, it's best to skip this step and choose more cooking methods like blanching, stir-frying, cold salads, and steaming.
Using Too High Oil Temperature
When stir-frying, many people like to "flash-fry" the oil first, especially heating the oil until it smokes before adding green onions and ginger to create a fragrant aroma. But by then, the oil temperature is often over 200°C. Vitamin E, phospholipids, unsaturated fatty acids, etc., in the oil are easily oxidized at high temperatures, and other nutrients in the vegetables are also destroyed.
In addition, when stir-frying, if the heat is too low and the cooking time is too long, a large amount of nutrients in the ingredients, such as vitamin C, anthocyanins, and chlorophyll, will be lost with the juices.
Therefore, it is recommended to add the ingredients to the pan before the oil smokes, and use a high-heat quick-stir-fry method to shorten the heating time.
Adding Salt Too Early
Many people have the habit of adding too much salt or adding it too early when stir-frying. This causes excessive juice to be exuded from the vegetables, not only causing nutrient loss but also making the dishes wilt and affecting the texture.
For meat, adding salt too early will cause the protein to coagulate prematurely, which is not only difficult to digest but also prevents the fishy smell from dissipating and the umami from the broth from seeping in. It is recommended to add salt when the dish is about 70-80% cooked, or just before serving.
Adding Vinegar to Green Leafy Vegetables
Many people like to add a little vinegar to enhance the flavor when stir-frying. However, if too much vinegar is added to green vegetables, the color will turn yellowish-brown, whereas adding vinegar to yellow or white dishes like shredded potatoes or lotus root slices has no such effect.
This is because green vegetables contain a large amount of chlorophyll and magnesium. After adding vinegar, the hydrogen in the acetic acid will immediately replace the magnesium in the chlorophyll, and this important nutrient is "stolen." Therefore, when cooking green leafy vegetables, do not add too much vinegar, and it's best not to add any at all.