Because of aflatoxin, phenylpropyl pyrene and nitrosamine, three strong carcinogens recognized in the world, food itself contains no or little, but it is often polluted during processing, storage, transportation and cooking.
Aflatoxin mainly exists in moldy grain, oil and peanuts. It is a metabolite of Aspergillus flavus and Aspergillus parasiticus, which is extremely toxic and can lead to liver cancer. As aflatoxin is a heat-stable chemical, it is not easy to be destroyed during cooking. Preventive measures are mainly mildew prevention. However, if the food is moldy and toxic, appropriate detoxification measures should be taken: for example, peanuts can be eliminated by mildew; Rice can be rolled with water; Vegetable oil with alkali can detoxify.
When organic matter and fossil fuel are not completely burned, a class of strong carcinogens-polycyclic aromatic hydrocarbons can be produced, and phenylpropyl (a) pyrene is its typical representative, which is widely found in nature. The main ways for it to enter food are: (1) environmental pollution. There are a lot of phenylpropyl (a) pyrene in smoke and automobile exhaust, which is transferred to plants through leaves and roots. (2) Unreasonable processing methods, such as smoking and barbecue, often cause food pollution due to dripping oil and burning. (3) Oil pollution is often caused by oil dripping when oil is squeezed or rolled. (4) The pollution of storage containers, such as beer, is often polluted because it is stored in asphalt-coated wine cans. (5) Directly imported food is polluted by dust during sales and transportation, which will also increase phenylpropyl (a) pyrene.
Phenyl propyl (a) pyrene, with stable chemical properties, is not easy to be destroyed during cooking, and can cause gastric cancer, adenocarcinoma, hematologic cancer, etc. After oral administration. In order to prevent phenylpropyl (a) pyrene from polluting food, we should first prevent environmental pollution, and do not plant leafy vegetables and oil crops in industrial areas and highways with serious air pollution. Secondly, improve unreasonable smoking and fire roasting processes to prevent engine oil pollution. In addition, eating more vitamin A and cruciferous plants such as cabbage and radish can prevent polycyclic aromatic hydrocarbon poisoning.
There are more than 100 kinds of nitrosamines. Different nitrosamines can cause different tumors, the most important ones are esophageal cancer, gastric cancer and liver cancer, which can induce tumors or deformities to future generations through placenta. Nitrosamines are formed by nitrite and secondary amines in protein, which are widely distributed in nature. Foods with high content include salted fish, shrimp skin, beer, bacon, nitrate sausage and so on. Put it for too long, it will also produce meat stuffing and vegetable stuffing. Rotten vegetables contain a lot of nitrate, which can be decomposed into nitrite by bacteria and saliva, and then nitrosamines are synthesized with secondary amines in protein in the stomach. When the pH value of gastric juice is 3, the formation of nitrosamines can be inhibited. When the pH value is 5, it can promote the formation of nitrosamines.
Therefore, it is necessary to control the content of nitrite in products and eat less stale bacon, salted fish, shrimp skin and other foods. Taking vitamin C can block the formation of nitrosamines and garlic can also block nitrosamines.
Medical scientists have found that more than 10 chemicals have carcinogenic effects, among which nitrosamines, benzopyrene and aflatoxin are recognized as the three major carcinogens, all of which are closely related to diet.
1. nitrosamines can cause tumors in almost all organs of human body, among which digestive tract tumors are the most common. Nitrosamines are commonly found in cereals, milk, cheese, tobacco and alcohol, bacon, barbecue, marine fish, canned food and drinking water. The content of nitrite in stale food (especially vegetables cooked for a long time) is high.
Second, benzopyrene is mainly produced in the combustion process of coal, oil, natural gas and other substances, and fat and cholesterol can also form benzopyrene at high temperature. The content of benzopyrene in smoked products such as sausages can be 60 times higher than that of ordinary meat. It has been proved that long-term exposure to benzopyrene will not only lead to lung cancer, but also lead to digestive tract cancer, bladder cancer and breast cancer.
Aflatoxin is the strongest carcinogen known. Medical scientists believe that aflatoxin is probably an important cause of liver cancer. In some areas with high incidence of liver cancer, people often eat fermented foods, such as tofu and bean paste. If this kind of food is not properly made, it is easy to produce aflatoxin.
In order to prevent the above-mentioned main carcinogens from causing trouble and reduce and weaken the threat of carcinogens to human beings, people must adopt scientific methods in food production, processing and cooking.