Pickled Foods: Four Tips to Prevent Nitrite
During autumn and winter, many families start to pickle foods like potherb mustard, Chinese cabbage, and sugar garlic. Experts remind that the main safety concern with pickled foods is pickled vegetables, especially short-term pickled vegetables, so-called "quick-pickled vegetables."
Pickling for over a month is safer
Associate Professor Fan Zhihong from the Department of Nutrition and Food Safety at the College of Food Science, China Agricultural University, pointed out that nitrites come from the high nitrate content in vegetables. Vegetables absorb nitrogen from fertilizers or soil, accumulating harmless nitrates. During the pickling process, some bacteria convert these nitrates into toxic nitrites, causing problems. Subsequently, the nitrites are gradually used or decomposed by bacteria; after reaching a peak concentration, they gradually decrease and eventually disappear.
Generally speaking, the highest nitrite content in pickles occurs between two to ten days after pickling begins. When the temperature is high and the salt concentration is low, the "nitrite peak" appears earlier. Conversely, when the temperature is low and the salt amount is high, the "nitrite peak" appears later. In northern China, pickling salted vegetables and sauerkraut usually takes over a month, while in southern China, pickling sauerkraut and pickled vegetables also takes over 20 days. Generally, after 20 days, the nitrite content has significantly decreased, and it is very safe after a month. The real threat to food safety is vegetables pickled for only two to ten days. Vegetables pickled for over a month can be eaten with confidence.
Experts also remind that when pickling, you can add some green onions, ginger, garlic, chili juice, or lemon juice. These substances can reduce nitrite content. For example, organic sulfides in garlic juice, vitamin C in lemon juice, and other reducing substances can block the synthesis of nitrosamines, which are carcinogens.
Chronic patients and children should not eat too many pickles
Many people enjoy eating pickled vegetables. Fan Zhihong stated that pickled vegetables contain dietary fiber and certain amounts of minerals like calcium, magnesium, and potassium. Lactic acid and acetic acid fermentation can also produce small amounts of B vitamins, so it is okay to eat a small amount of pickles as an appetizer.
However, it is not appropriate to use pickles as a main dish or a substitute for fresh vegetables. Especially for chronic patients and children, who need to eat more fresh vegetables to prevent disease or promote growth and develop a healthy dietary habit of light flavors, they should not eat too many pickled vegetables.
Pickled Foods: Beware of Excessive Salt and Sugar
Experts also stated that salt or sugar is the main ingredient for pickling foods. Sugar-pickled vegetables do not produce toxic substances, but for long-term preservation, the sugar content needs to be over 65%, which brings the problem of high sugar and high calories. For salt-pickled vegetables to be preserved for a long time, the salt content also needs to be around 15%, making the flavor too heavy and easily raising blood pressure. Although most pickle products now use a combination of sugar and salt and reduce the saltiness.
But no matter how high-quality the pickled vegetables are, they are still foods containing relatively high amounts of salt and sugar. Compared to fresh products, pickled vegetables and fruits have significant losses in nutrients. From a nutritional health perspective, it is better to eat fresh vegetables and fruits directly.
-Expert Tips
Four Tips to Prevent Nitrite
As is well known, pickles can easily have high nitrite content, but Fan Zhihong reminds that foods that can easily produce nitrites in daily life are far more than just pickles. Leftovers, cold dishes, long-cooked hot pot soups, and dried seafood are all "high-incidence areas" for nitrite production.
1. Leftovers—Reheat before eating
The nitrite content in vegetables will rise after storage, and it will also produce nitrites after cooking, because many bacteria can convert nitrates in vegetables into nitrites. After a meal, if leftovers are put in the refrigerator, bacteria will also breed slowly, and the longer they are stored, the more nitrites are produced. Experts remind that if stir-fried dishes are promptly put in the refrigerator after a meal and eaten the next time, the amount of nitrite produced is actually not as large as imagined and will not reach the level of causing poisoning or cancer. If the vegetables are blanched before stir-frying or mixing, most of the nitrites have been lost in the water, so if there are leftovers, even less nitrite will be produced.
However, for long-term safety, if a large plate of vegetables cannot be finished, you can set aside a portion in advance, let it cool to room temperature, and then put it in the refrigerator. This way, it has less contact with bacteria, less nitrite is produced, and it can be safely reheated for the next meal.
2. Cold Dishes—Add minced garlic, lemon juice, or vinegar
Although cold dishes may still look fresh and crisp after a few days, their nitrite content after one or two days is even higher than that of leftovers. Adding a large amount of minced garlic, vinegar, or lemon juice can inhibit bacterial growth and effectively reduce nitrite content. Moreover, cold dishes are best eaten within 24 hours.
3. Hot Pot Soup—Safest to drink within the first half hour of cooking
The nitrite content in different soup bases varies greatly after cooking. When sauerkraut or seafood is used as the base, the nitrite content will be particularly high because sauerkraut is a pickled vegetable, and seafood is also an ingredient high in nitrites and nitrosamines. In comparison, clear soups, bone broth, and yin-yang soups are relatively safer. When eating hot pot, it is best to drink the soup within half an hour and not drink it after an hour. For sauerkraut and seafood soups, it is best to drink them at the beginning to avoid excessive intake and danger.
4. Seafood Products—Be cautious of those with a pungent smell
Seafood is highly nutritious, but dried shrimp, small fish, shredded squid, dried fish fillets, and salted fish all contain nitrites, and frequent consumption can increase the risk of cancer. Therefore, before eating all foods like dried shrimp, small dried shrimp, fish fillets, and shredded squid, you should smell them carefully. If they do not seem fresh and have a pungent odor, they must contain a lot of nitrosamine substances. (Intern reporter Li Rui)