Do overnight dishes cause cancer? Can you eat? We use 30 dishes to test and tell you the answer
Every time after the New Year, many friends complain about one thing: after eating leftovers for many days, they are tired of eating! The point is that leftovers have 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 News, on March 1, an old man in his 60s in Changzhou suddenly fainted and was pronounced dead after 40 minutes of rescue. It is understood that the deceased had been eating leftovers from the Chinese New Year in recent days, and then had diarrhea. It was not until a dozen times a day that he went to the hospital to see him. However, he fainted on the way to treatment.
This may be acute enteritis caused by eating leftovers. Severe diarrhea causes electrolyte imbalance in the body, severe acidosis and hyperkalemia, which are life-threatening.
If you forward this news to your relatives, it will definitely become a topic of conversation. The older generation will say: "Can't eat overnight vegetables? Decades ago, we went to boarding school and went home once a week, bringing with us soda cabbage. To eat for a week, which one will have cancer."
Can "overnight dishes" and "leftovers" be eaten? It seems that we need to have a good experiment.
- Does not cause cancer, an experiment tells you
In order to find out whether overnight dishes are carcinogenic, Ningbo Food Inspection Institute conducted a scientific experiment to detect the nitrite content and the number of bacteria in the overnight dishes.
The researchers selected 32 common raw materials on 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 placement times and placement environments of the overnight dishes. The placement time was 0 hours, 6 hours, 12 hours, and 24 hours, and the placement environment was normal temperature placement and refrigerator refrigeration.
When the standing time was reached, the experimenters checked the nitrite content and the total number of colonies produced in the overnight dishes.
The inspection methods are based on "GB5009.33-2016 National Food Safety Standard for Determination of Nitrite and Nitrate in Food" and "GB4789.2-2016 National Food Safety Standard for Determination of Total Colonies 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. Let's "focus" for you:
- Under different storage time and storage environment, the nitrite content produced by overnight dishes was different. Overnight dishes placed at 4°C for 24 hours have a nitrite content of less than 1 mg/kg, which poses no risk to human health.
- In the overnight vegetables placed at 25°C for 12 hours, the nitrite content of the overnight vegetables of leafy vegetables increased significantly, even exceeding 20mg/kg, which is a food safety risk, but the content of nitrite in the overnight vegetables of meat changed. Not much.
- Judging from the total number of colonies, the overnight cold dishes are more likely to breed bacteria than other cooked dishes. 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!
Second, please accept some suggestions!
From the experimental results, we can know that it is not impossible to eat overnight dishes, but before eating, we must check these 3 points. First, look at the type of overnight dishes; second, look at the storage conditions of the overnight dishes, whether it is room temperature or low temperature; Storage time for overnight dishes. If it is stored at room temperature for too long, the nitrite content and the number of bacteria will greatly increase, and it is not suitable for consumption.
The old man who died suddenly at the beginning of the article was tragic because he ate leftovers that had been stored for too long, leading to bacterial enteritis.
Finally, the researchers concluded a few recommendations:
Store at low temperature, the amount of nitrite and bacteria produced by overnight dishes are less than those stored at room temperature, so they should be stored in the refrigerator;
Cold dishes have not been overheated. Whether it is stored at low temperature or at room temperature, if they are stored for too long, it is easier to breed a large number of microorganisms. Therefore, cold dishes are recommended to be cooked and eaten immediately;
Leafy vegetables overnight under normal temperature conditions, after more than 12 hours, the rate of nitrite production will be greatly accelerated, so try not to store leafy vegetables overnight;
Overnight dishes should be stored separately at low temperature, do not mix together, so as to avoid cross-infection, when stored in the refrigerator at low temperature, cover with a layer of plastic wrap;
Before eating the overnight dish, it should be heated to 100°C and boiled for more than 3 minutes; kill microorganisms;
Eat less overnight dishes, you can reduce the intake of nitrite and minimize the risk of food safety.
The amount of nitrite 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 should not be stored; root vegetables, mushrooms, etc., can be stored at low temperature for 1-2 days without affecting the taste; meat can be properly preserved, but It needs to be frozen, and the freezing time should not be too long.
- Nitrite is a food additive
In fact, nitrite is widely found in food, especially grain, vegetables, meat, etc., which itself contains a certain amount of nitrite.
In addition, nitrite is widely used in food processing as a color retention agent and preservative. However, the state has strict regulations. The maximum residue 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 for human consumption. However, if the intake exceeds the standard, nitrite will synthesize nitrosamines with certain protein decomposition products, which will play a carcinogenic role.
Instead of worrying about nitrite levels in overnight dishes, focus on microbial contamination, which is more dangerous to your health.
Some people are used to cooking a lot of dishes at a time and putting them in the refrigerator if they can't finish them. In order not to waste it, some people bite the bullet and eat the leftovers. In fact, this is not good for health. The food is always fresh, and it is the most sensible way to eat as much as you eat.