Except for some varieties like microgreens, most vegetables should be cut before cooking. Many people have the habit of cutting vegetables first and then washing them, but they don't realize that many nutrients and beneficial substances in vegetables are water-soluble. Washing finely cut vegetables causes a large loss of nutrients into the water. The correct method is to wash first, then cut.
Squeezing vegetable juice—improper disposal
When preparing fillings for dishes like wontons or dumplings, vegetables need to be finely chopped, which produces a large amount of juice. Some people squeeze out the juice to make the filling easier to shape or handle, discarding 70% of the vitamins and minerals in the vegetables.
The correct approach is to chop the vegetables along with ingredients like dried tofu, mushrooms, and meat, and mix them well to allow the vegetable juice to seep into the other ingredients. Additionally, some people eat bean sprouts but only eat the sprouts, not the beans. In fact, the beans contain three times more vitamin C than the sprouts.
Stored for too long—destruction of vitamins
Some people buy a large quantity of vegetables at once and eat them over several days. The result is not only a poor texture but also a gradual loss and destruction of vitamin C. Vegetables contain nitrates, which in the air are converted into nitrites. Nitrites can turn normal hemoglobin into methemoglobin, which loses its ability to carry oxygen, causing symptoms such as cyanosis of the nails and lips, and even shortness of breath throughout the body. Vegetables have a high water content and are prone to mold growth, producing various mycotoxins. These toxins can not only adhere to the surface but also penetrate deep into the vegetable. Even heating cannot destroy these toxins, so vegetables should be eaten as fresh as possible.