Many salt will be added during the processing of pickled foods to make the food antiseptic better. But this kind of food will produce a lot of harmful substances such as nitrite and nitrite due to the reproduction of microorganisms. Nitrate in pickled vegetables may be reduced to nitrite by microorganisms. Derivatives of proteins in such preserved foods together with nitrite can generate a carcinogen, amine nitrite, which is harmful to the body and can cause cancer.

　　Pickled vegetables are not well marinated , It will directly contain the carcinogen nitrite, which is why excessive nitrosamines have been detected in Cantonese salted fish. In addition, nitrate and nitrite in preserved foods can synthesize nitrite with secondary amines in meat, causing gastric cancer. Sausages, salted fish, cured ham are artificially added to nitrite for color development, flavor enhancement, antisepticity, etc., which also increases the possibility of producing nitrite, so you should control your intake.

　　 Although preserved food has many health risks, if you take some correct eating methods, you can enjoy the food while retaining its nutrition to the maximum extent and reducing its harm. The reduction in consumption will inevitably lead to a reduction in salt, nitrate, and nitrite intake. As long as the intake is controlled within a certain range, there will be no harm to health or negligible harm.

　　Additionally salted foods, when the amount of salt added is less than 12％, when the temperature is higher than 20 ℃, the nitrite content tends to peak in 7-8 days, nitrite after 20 days of pickling The resulting peak will be minimized. If the temperature is low, the rising and falling curve of nitrite content will be delayed for one to two weeks. Generally, the salt content of preserved food should be above 15％ to inhibit the activity of microorganisms. And choose to eat when the nitrite content drops to the minimum.