Which pickled foods contain more nitrite? In fact, the main safety problem is kimchi, and it is pickled for a short time, which is the so-called "kimchi". Vegetables pickled for more than a month can be assured. It turns out that nitrite comes from nitrate with high content in vegetables. Vegetables absorb nitrogen from nitrogen fertilizer or soil, accumulate non-toxic nitrate, and then are converted into toxic nitrite by some bacteria during pickling, which brings trouble. Later, nitrite was gradually utilized or decomposed by bacteria, and after the concentration reached a peak, it would gradually decrease or even disappear.
Generally speaking, the most nitrite in pickles occurs between two or three days and ten days after the start of pickling. When the temperature is high and the salt concentration is low, "nitrite peak" appears earlier; On the contrary, when the temperature is low and the salt content is high, it appears later.
Pickling pickles and sauerkraut generally takes more than one month in northern China and more than 20 days in southern China. It is generally safe to eat out at this time. Traditional pickles take a long time to make sauce, even as long as several months, so there is no need to worry about nitrite poisoning. Strict isolation of oxygen in kimchi processing can reduce the production of harmful substances, adding garlic in kimchi can reduce the production of nitrite, and good technology and strains will also reduce the risk.
The real danger is the vegetables that are only preserved for two or three days to ten days. Some families like to cook pickles for a short time, and also like to put cold dishes for two days before eating. These are all unsafe practices. Because of eating pickled fish and other vegetables, there have been many cases of nitrite poisoning, mainly because the pickled vegetables have not been marinated for enough time and were sold in advance.
It should be noted that salt and sugar are mainly used for curing food because they can control the properties of microorganisms under high osmotic pressure and help to produce special flavor and taste. Sugar stains will not produce toxic substances, but in order to achieve the effect of long-term preservation, the sugar content should reach more than 65%, which will bring trouble of high sugar and high calorie. In order to achieve a good long-term preservation effect, salting should also reach about 15% salt, which is too strong and is suspected of raising blood pressure. So at present, most pickles products use sugar and salt, and the salinity is reduced, which is easy for consumers to accept. However, such low-salt pickled food will inevitably be difficult to preserve, and it is inevitable to add preservatives.
Nitrite is produced in pickled food, on the one hand, there are factors such as temperature and curing time, on the other hand, there are a lot of nitrate in raw materials. Duck eggs, tofu and other foods do not contain a lot of nitrate, so it is impossible to produce a lot of nitrite after pickling. The unhealthy factor is just too much salt itself.
But because water pollution is not uncommon in China, aquatic products may contain more nitrite. In the process of drying or curing, some protein decomposes to produce amines, which combine with nitrite to become carcinogenic nitrosamines, which is indeed a problem that cannot be ignored. The determination shows that there are nitrosamine pollution problems in salted fish, shrimp skin, dried seafood, dried fish fillets and shredded squid, and the products that are damp and have bad taste are particularly worrying.
Generally speaking, kimchi, pickled cabbage, pickled cabbage, pickled cabbage and other foods made according to science and technology and preserved for a long time will not cause poisoning, are safe to human body, and can also provide some minerals and cellulose. Salted duck eggs, bacon, fermented bean curd and preserved fruit without peculiar smell will not produce a large number of carcinogens such as nitrosamines. However, compared with fresh products, pickled vegetables and fruits lose more nutrients, and the content of salt or sugar is too high. From the point of view of nutrition and health, it is better to eat fresh vegetables and fruits directly.