In fact, these seemingly different problems roughly explain one thing: cooking with vegetable oil will bring soot, and everyone may suffer. In fact, the severity of the oil fume problem is related to the type of oil and the specific cooking methods.
Smoke exposure and lung cancer risk
China people are used to eating delicious stir-fried dishes, which are often associated with greasy and dirty kitchens and chefs whose faces, hair and even bodies are covered with oil fumes. In fact, lampblack not only means harm to the skin and pollution to the environment, but also does great harm to health. The reason why pregnant women hate lampblack is precisely because the embryos in the first trimester are particularly sensitive to harmful substances. At this time, the expectant mother's sense of smell is obviously enhanced, that is, she instinctively tries to stay away from harmful substances such as soot and prevent them from harming the fetus. Even if they are not pregnant, ordinary people don't like strong fumes because the body knows they are harmful.
In China, lung cancer is the first most common cancer for men and the second most common cancer for women. Interestingly, 15% of male lung cancer patients and 53% of female lung cancer patients do not smoke-but they usually cook a lot. Scientific research has long found that cooking fume is one of the important pathogenic factors of lung cancer, especially among non-smoking women, which can not be ignored.
American researchers have compiled 29 population-based surveys. In 22 epidemiological studies, 18 studies found that there was a correlation between soot exposure and lung cancer risk. Four other studies have found theoretical evidence that carcinogenic air pollutants in the kitchen are related to human health. Two studies found that the amount of 1- hydroxypyrene (the index of metabolites of 1-OHP, 1- hydroxypyrene and polycyclic aromatic hydrocarbons carcinogens in male restaurant staff urine samples) was related to the DNA damage index. Another retrospective study in Britain also found that the professional history of being a chef increases the risk of lung cancer. In other words, although there is no long-term follow-up survey, many studies have suggested that frequent exposure to lampblack will increase the risk of lung cancer. In addition, women who have been engaged in Chinese cooking for a long time have increased the prevalence of respiratory diseases and decreased their lung ventilation ability. These views have been widely recognized by researchers at home and abroad.
Which oils have the most carcinogens after heating?
Many people will immediately ask when they see this: which oils produce the most carcinogens after heating at high temperature? What kind of oil smokes most easily?
Recently, a scientific news in the British Daily Telegraph reported that chemical analysis experts at the University of De Montford in the United Kingdom found that oils rich in polyunsaturated fatty acids, such as corn oil and sunflower seed oil, produced the most aldehyde carcinogens when cooking. Using them to cook a "fish and chips" fast food, the content of carcinogenic aldehyde is 100 ~ 200 times higher than the relevant health standards of the World Health Organization. In contrast, if you switch to olive oil, butter or coconut oil, the harmful substances produced will be greatly reduced.
In fact, previous studies have confirmed that cooking fume produced by soybean oil, sunflower oil and lard contains aldehyde carcinogens t-t-2,4-DDE, t-t-2-NDE,
T-2, CA and t-2-UDA. Among edible oils, soybean oil produces the most t-t-2 and 4-DDE, which is 85% higher than sunflower oil. These substances are genotoxic and cytotoxic to human lung epidermal cells, which will significantly reduce the activities of various antioxidant enzymes and increase the production of reactive oxygen species.
These studies show that the "polyunsaturated fatty acids" often advertised in daily advertisements are actually unstable to heat and are more likely to produce toxic carcinogens when heated at high temperatures. At the same time, they are prone to thermal oxidation polymerization and generate "sticky" substances, which make it difficult to clean the range hood and cast a layer of dirt on the kitchen that cannot be washed away. Comparatively speaking, lard has a better heat temperature and produces less oxidized polymer, so the cooker is "less sticky".
Therefore, it is very important to choose oil which is not easy to be oxidized, has better thermal stability and higher smoke point. Compared with clear and transparent oil, "earth-squeezed" crude oil has more impurities and produces more soot at the same temperature. The residual oil after frying is more likely to smoke than the fresh clarified oil. It is extremely unwise to stir-fry with them often. Don't think that frying with "home" and "traditional" methods is healthier.
How to stay away from cancer risk
A study investigated 6 1 cooking soldiers in the army. It was found that after 5 days of exposure to cooking fumes, the contents of PAHs metabolite marker 1- hydroxypyrene, DNA damage marker 5- hydroxydeoxyguanine and oxidative stress marker isoprostaglandin in their urine increased significantly, which was higher than that of soldiers who were not exposed to cooking fumes. In addition, there is a significant correlation between the logarithmic concentrations of polycyclic aromatic hydrocarbons metabolites, oxidative stress metabolites and DNA damage markers in blood. To put it simply, after staying in an environment with a lot of oil smoke for a few days, the carcinogens in the blood of cooking soldiers increased, the damage degree of genetic materials also increased, and the substances that promoted aging increased. These studies show that if we can reduce the frequency of cooking, increase the proportion of cooking methods such as cooking, cold salad and blanching, and reduce the proportion of fried cooking, we can reduce the degree of harm.
The study also found that indoor ventilation is related to the risk of lung cancer. Not only cigarette smoke is the source of PM2.5, but also soot. A cigarette can make the concentration of inhalable particles in the house greatly exceed the standard, and the soot next to the iron pot can easily raise the PM2.5 value to more than 200. The more harmful substances people inhale indoors, the greater the harm to health. Therefore, timely and effective ventilation is very important to reduce oil smoke pollution.
Excessive cooking methods will produce more carcinogens.
Of course, under the same air pollution, not everyone who cooks will get lung cancer. Many studies have found that the susceptibility to lung cancer has a certain genetic basis. For people with susceptible genes, long-term exposure to air pollution may make the situation worse and increase the risk of lung cancer. Since you are not sure whether you have a super anti-pollution gene, it is wise to take the initiative to stay away from soot pollution. To sum up, the following measures can be taken to prevent the harm of oil fume and avoid the risk of cancer:
1. Don't use crude oil and crude oil squeezed by indigenous methods, and don't reuse the residual oil left over from previous cooking. Because there are many impurities in unrefined oil and residual oil, and the smoke point is low, more lampblack will be released when cooking.
2. When cooking, reduce the proportion of soybean oil, corn oil and sunflower oil (these oils contain more unsaturated fatty acids), and give priority to oils with good thermal stability, such as refined tea seed oil, refined olive oil, mustard oil, etc., and edible oil with monounsaturated fatty acids as the main component. If you really need high-temperature cooking and frying, it is recommended to choose oils with high saturation and more stability to heat, such as palm oil and coconut oil.
3. Reduce the proportion of dishes that need high-temperature heating, such as frying, frying, stewing and griddle, and increase cooking methods such as steaming, boiling, stewing, stewing and cold salad. For example, a steamed fish with black bean sauce, a fried seaweed and broccoli, a cold fungus and cucumber, and a fried shredded pork with onions and carrots. This dish is also rich and balanced in nutrition, but it is much less than the oil smoke of four fried dishes.
4. Reduce the cooking oil temperature. In view of the smoke point of pure oil as high as 190℃, normal cooking temperature can be reached without obvious smoke. As soon as you see a little smoke, put the food in immediately. The temperature is just right. In fact, how to judge the oil smoke can be tested by a piece of onion skin or garlic: there are many bubbles around, but they will not change color immediately. Put an end to the "overheating" cooking method in the pot. This method will not only produce lampblack, but also directly expose the ingredients to high temperature, producing more carcinogens.
5. Buy a pot with thick body and large heat capacity. Because the heat capacity of the pot is large, it takes time to heat it, so that the smoke in the pot will not roll before the vegetables are put in. It takes several times to get used to this kind of pot, and you may not be able to grasp the time of putting vegetables at first. But once you get used to it, you will enjoy the happiness of less oil smoke and the food will be more refreshing and delicious.
6. Buy a range hood with strong suction. When installing, pay attention to the reasonable height from the stove, not too far away, and ensure that the suction is strong enough, so that you can't smell the cooking from the stove 1 meter.
7. Turn on the range hood before turning on the stove, and continue to smoke for 5 minutes after cooking, so as to ensure that the incompletely burned waste gas and lampblack are sucked away. At the same time, open the nearby windows and let in fresh air.
8. Wear a hat and long-sleeved overalls when cooking, then change the overalls in time and clean them regularly. Wash your hands and face after you leave the kitchen.
9. When baking greasy food (such as grilled fish, grilled chicken wings, grilled ribs, etc.). If you use an air fryer, you should pay attention to putting the air fryer next to the range hood. Because when using high-temperature hot air to "dry fry" fatty foods, a certain amount of smoke will be produced, which inevitably contains harmful substances produced by fat heating.
10. At present, there are many studies on "the harm of PM2.5 to pregnant women and children" at home and abroad. Pregnant women and lactating mothers are advised not to cook food with lampblack and stay away from the kitchen where lampblack is rolling. Eat less fried food. According to foreign research results, eating more fried foods may increase the risk of children suffering from asthma, allergies and other diseases in the future.