Do overnight vegetables cause cancer? Can I eat it? We use 30 dishes to test and tell you the answer
Every time the Chinese New Year is over, many friends will complain about one thing: After eating leftovers for many days, they are tired of eating! The key is that leftovers contain a lot of nitrite, which is carcinogenic and unhealthy to eat!
And a recent piece of news tells us that eating leftovers may really be risky.
According to Modern Express, on March 1, an elderly man in his 60s in Changzhou suddenly fainted and was declared dead within 40 minutes of rescue. It is understood that the deceased had been eating Chinese New Year leftovers in recent days, and then developed diarrhea. He didn't want to see the hospital until he had diarrhea more than a dozen times a day, but he fainted on the way to the treatment.
This may be acute enteritis caused by eating leftovers. Severe diarrhea leads to electrolyte imbalance in the body, severe acidosis and hyperkalemia, which are life-threatening.
If you forward this news to your loved ones, it will definitely become a hot topic, and the older generation will say: "You can't eat overnight vegetables? Decades ago we went to boarding school and went home once a week, and the pickled vegetables we brought with us You have to eat it for a week, and whoever eats it will cause cancer.”
Can "overnight dishes" and "leftovers" be eaten? It seems that we need to experiment a lot.
- Whether it causes cancer or not, an experiment tells you
In order to find out whether overnight vegetables are carcinogenic, Ningbo Food Inspection Institute conducted a scientific experiment to detect the nitrite content and bacterial count in overnight vegetables.
The researchers selected 32 common raw materials in the market, including meat, eggs, vegetables, etc., and cooked them into 30 home-cooked dishes according to the eating habits of ordinary residents.
Next, the researchers simulated different storage times and storage environments for overnight dishes. The storage time was 0 hour, 6 hours, 12 hours, and 24 hours. The storage environment was normal temperature storage and refrigerator storage.
When the storage time was reached, the experimenters tested the nitrite content and the total number of colonies produced in the overnight vegetables.
The inspection methods are based on "GB5009.33-2016 National Food Safety Standard for the Determination of Nitrite and Nitrate in Food" and "GB4789.2-2016 Food Safety National Standard for the Determination of the Total Bacterial Colony in Food Microbiological Inspection".
The test results are compiled into a table for comparison:
①Comparison of nitrite content
②Under refrigeration, colony comparison
③At room temperature, colony comparison
Analyzing the test results, we can draw some conclusions. Here are some key points for you:
- Under different storage time and storage environment, the content of nitrite produced by overnight vegetables was different. The nitrite content of overnight vegetables placed at 4°C for 24 hours is less than 1 mg/kg, which is no risk to human health.
- Leave overnight vegetables at 25°C for 12 hours, and the nitrite content of leafy overnight vegetables rises significantly, even exceeding 20mg/kg, which poses a food safety risk, but the nitrite content of meat overnight vegetables changes not big.
- From the perspective of the total number of colonies, overnight cold dishes are more likely to breed bacteria than other dishes that are cooked thoroughly. When stored at room temperature, the number of microorganisms increases exponentially!
In general, the safety of overnight dishes is closely related to the type of dishes, storage conditions and storage time!
Two, some suggestions, please keep them well!
From the results of the experiment, we can know that it is not impossible to eat overnight vegetables, but before eating, we must first check these 3 points. One is to look at the type of overnight vegetables; Storage time for overnight dishes. If it is stored at room temperature for too long, the nitrite content and the number of bacteria will increase greatly, and it is not suitable for consumption.
The old man who died suddenly at the beginning of the article was tragic because of eating leftovers that had been stored for a long time, leading to bacterial enteritis.
Finally, the researchers concluded with several recommendations:
Stored at low temperature, the amount of nitrite and bacteria produced by overnight vegetables is less than that stored at room temperature, so it should be stored in the refrigerator;
The cold salad has not been heat-processed, whether it is stored at low temperature or at room temperature, if it is stored for too long, it is easier to breed a large number of microorganisms. Therefore, it is recommended to cook the cold salad and eat it now;
Leafy vegetables overnight at room temperature, after more than 12 hours, the rate of nitrite production will be greatly accelerated, so try not to store leafy vegetables overnight;
Overnight vegetables should be stored separately at low temperature and not mixed together to avoid cross-infection. When storing in the refrigerator at low temperature, cover with a layer of plastic wrap;
Before eating overnight vegetables, heat to 100°C and boil for more than 3 minutes; kill microorganisms;
Eating less overnight vegetables can reduce the intake of nitrite and minimize the risk of food safety.
The nitrite content produced by different overnight dishes is different, so we have to deal with it differently.
For example, green leafy vegetables, soy products, seafood, cold dishes, etc. should be eaten as a meal and not stored; root vegetables, mushrooms, etc. can be stored at low temperature for 1-2 days without affecting the taste; meat can be stored properly, but It needs to be frozen, and the freezing time should not be too long.
- Nitrite is a food additive
In fact, nitrite widely exists in food, especially grain, vegetables, meat, etc., which itself contains a certain amount of nitrite.
In addition, nitrite is widely used as a color protectant and preservative in food processing. However, the country has strict regulations. The maximum residue amount in meat products is 30 mg/kg-70 mg/kg. As long as it is a food that meets the regulations, there is no safety risk when people eat it. However, if excessive intake, nitrite will synthesize nitrosamine compounds with certain protein decomposition products, which will cause cancer.
Instead of worrying about the nitrite content of overnight vegetables, it is better to focus on microbial contamination, which is more harmful to your health.
Some people are used to cooking a lot of dishes in one meal, and put them in the refrigerator if they can't finish them. In order not to waste, some people bite the bullet and eat up the leftovers. In fact, doing so is not good for your health. Food should always be fresh. It is wisest to cook as much as you eat.