Blanching is a common process when cooking, but can you really blanch water? Which ingredients need to be blanched, cold or hot? Blanching, doing it right is healthy, and doing it wrong will greatly reduce nutrition and taste~ In this article, we will take an inventory of the ingredients that need to be blanched and how to blanch it correctly.
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Which ingredients need to be blanched? 1. Vegetables high in oxalic acid
Oxalic acid is an anti-nutrient found in many vegetables, but there are differences in content. Excessive intake of oxalic acid in the daily diet can form insoluble substances with calcium before absorption, hinder the absorption of calcium, and after absorption, it can form poorly soluble oxalate with calcium and other substances in the body, increasing the risk of stones.
Vegetables such as Chinese cabbage, white radish, cabbage, mung bean sprouts, carrot tasseled and other vegetables have very low oxalic acid content and can be eaten with confidence. Spinach, hollow vegetables, celery, amaranth, purslane and other vegetables have relatively high oxalic acid content, and need to undergo certain pretreatment to remove oxalic acid before eating. Fortunately, oxalic acid is easily soluble in water, and hot water blanching can remove most of oxalic acid. Studies have shown that when 180g of spinach is blanched in 1000ml of boiling water for 1 minute, 2 minutes, 3 minutes and 4 minutes, the removal rates of soluble oxalic acid are 43%, 50%, 54.7% and 58.9%, respectively. The removal rate of oxalic acid in spinach is not good for oil stir-frying, which does not exceed 5%, and even if the amount of cooking oil is increased, it has little effect. In addition, purslane is more special, its oxalic acid content is as high as 1460mg/100g, which is more than twice that of spinach. Experiments have shown that 100g of purslane is blanched with 500ml of water for 3 minutes, the oxalic acid removal rate can reach more than 50%, and the soup is discarded after 4 minutes of blanching for consumption, and the oxalic acid content is 560mg/100g. Although the content of this oxalic acid is lower than that of fresh spinach, it is still higher than most green vegetables, so it is better to eat less. 2. "Toxic" vegetables Some vegetables have their own toxins, if not blanched or eaten raw may cause food poisoning, serious will be fatal. (1) Beans, green beans
Raw beans and green beans contain saponins, which contain hemolysin that can destroy red blood cells, which has a strong stimulating effect on the mucosa of the gastrointestinal tract, causing congestion, swelling and hemorrhagic inflammation, which can cause nausea, vomiting, abdominal pain, diarrhea and other symptoms.
This ingredient is more heat-sensitive, heated for more than 10 minutes at 100 °C, or fried at a higher temperature, which can lyse saponins and eliminate the toxicity of harmful substances. Blanching water before cooking is a good way to avoid poisoning.
(2) Fresh yellow cauliflower
Certain ingredients in fresh yellow cauliflower can cause nausea, vomiting, dry mouth, and diarrhea when consumed. As for what this ingredient is, it is not yet clear. In the past, people thought that it was colchicine, but the latest research put forward different views on the "toxic components" in yellow cauliflower, believing that yellow cauliflower does not contain colchicine, contains a number of compound co-outflow components, soluble in water, can be decomposed by steam and blanching, and boiling water treatment for 3~5 minutes can be safely consumed. (3) Vegetables with high nitrite mention "nitrite", and many people will think of "carcinogenic". In fact, nitrite itself is not carcinogenic, but after it is eaten by us, it will produce nitrosamines in the environment of stomach acid, nitrosamines are carcinogens, excessive intake will increase health risks.
Therefore, vegetables with high nitrite content must be blanched before cooking. Some researchers evaluated the health and safety level of vegetables in a suburban area of Shanghai, and found that the nitrite content in fresh vegetables was generally low, the highest nitrite content in leafy vegetables was 19mg/kg, the nitrite content of onions and garlic, melons, beans, aquatic and nightshade fruits was lower, and the nitrite content of some vegetables was less than 0.1mg/kg.
Although you can eat it with confidence, the nitrite content of leafy vegetables is higher than that of other vegetables, and the toon nitrite content in leafy vegetables is more prominent. Don't worry, though, blanching water can reduce the nitrite content in vegetables. Someone bought 6 samples of toon from farmers markets and supermarkets, nitrite content is 100~500mg/kg, cleaning 3 times can remove more than 50% nitrite, its nitrite content is 50~200mg/kg, blanching for 1 minute can remove more than 90% of nitrite, and its nitrite content is 10~50mg/kg. Therefore, do not eat the dipping sauce again, even if it is scrambled eggs, you must blanch it first. (4) Vegetable aquatic plants that may be contaminated by parasites are likely to be contaminated by parasites, such as water chestnuts, lotus roots, water chestnuts that we often eat, do not directly use them as cold vegetables, it is likely to be infected with ginger fasciola, mild abdominal pain diarrhea, nausea and fever, severe cases will also cause intestinal obstruction, and even death.
Blanch the water and then mix it cold to ensure the safety of eating.
(5) Vegetables that are not easy to clean
Some vegetables have uneven surfaces, more potholes, easy to hide dirt, and more likely to have pesticide residues. For example, broccoli, cauliflower, and fungus are not easy to clean, and there may be soil and insect eggs in the crevices. However, broccoli is still relatively rich in vitamin C in vegetables, blanching time is not too long, to avoid vitamin C loss, generally blanched for 1~2 minutes. (6) Animal foods such as ribs, mutton, pork intestines and other animal foods with blood stains or special odors may carry blood stains or odors, and blanching can reduce their impact and improve the quality of dishes. While blanching, you can add cooking wine, fragrant leaves, star anise and other spices to increase the flavor.
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Things you must know before blanching
Blanching seems simple, it seems to be a matter of "boiling water + ingredients", but there are still many precautions in actual operation.
1. Meat under cold water, seafood, vegetables hot water
Meat foods need a pan under cold water to help skim away blood droplets. If the boiling water pot will denature the protein on the surface of the meat, the outermost layer is directly cooked, resulting in the blood and water inside not coming out, can not achieve the purpose of removing blood stains, and the taste is not good.
Vegetables need to wait for the water to boil before cooking. Although cold blanching has a higher removal rate than hot blanching, cold blanching will cause the physical structure of vegetables to be destroyed as much as possible, and more nutrients will be lost. It is recommended to blanch fish and shrimp in boiling water for 1~2 minutes and then take out, which can not only remove fishiness, but also maintain a tender taste. 2. The amount of water should be enough to flood the ingredients, so as to ensure that after adding the ingredients, the water in the pot can boil again in a short time, shorten the cooking time and reduce nutrient loss. 3. The blanching time of different ingredients is different
For leafy vegetables most only need to blanch for 1 minute, in addition, it is recommended to blanch water before cutting vegetables, immediately put it in cold water to cool down after blanching, drain it, do not squeeze too much, to avoid nutrient loss.
Vegetables such as bamboo shoots and cocoon can be boiled for a while. This is because the total oxalic acid removal rates of bamboo shoots and cocoon white are 60% and 10.7%, respectively, and the total oxalic acid removal rates of bamboo shoots and cocoon are 63.9% and 31.7%, respectively, when boiled for 3 minutes. At the same time, their own heat-afraid vitamin content is also very small, bamboo shoots, cocoon white vitamin C content is only 5mg/100g, vitamin B family is not more than 0.1mg/100g, do not worry about the loss of such nutrients. Blanch broccoli, cauliflower and fungus for 1~2 minutes; Water chestnuts, lotus roots, etc. should be blanched in boiling water for more than 1 minute; It is recommended to blanch beans and green beans for more than 10 minutes; It is recommended to blanch fresh yellow cauliflower for 3~5 minutes. After the meat is put into the pot, wait for the water to boil, and cook for another 1~2 minutes until there is no large amount of blood foam boiled out. 4. If the vegetables want to maintain their color, you can drop a few drops of edible oil when blanching 5. Do not reuse the water oxalic acid dissolved in the water after blanching, the longer the blanching time, the higher the content of oxalic acid in the soup. If you don't know if the vegetables you want to eat need to be blanched, then simply make boiled dishes. Drain the vegetables after they are out of the pan, add steamed fish soy sauce or light soy sauce, and drizzle with sesame oil or flaxseed oil, and it's a delicious dish! Boiling belongs to low-temperature cooking, compared with stir-frying, frying, frying can retain more nutrients, but also avoid the production of harmful substances, very recommended Oh~
Source: Popular Science China