Refrigeration at 4℃ and frozen storage at-18℃ are the general set temperatures of household refrigerators, which are also the best conditions confirmed by science. Many people regard the refrigerator as a universal storage box, especially the freezer, and think that things will never go bad as long as they are put in the freezer. It is not uncommon for many families to freeze food in the refrigerator for half a year or even a year. There are still many people who always like to stuff the refrigerator full and don't want to throw away expired food, thinking that it will not expire if it is frozen.
Interpretation of the truth:
10 June1/0/day, there was a news report on the internet:10 On June 5, a family dinner in Jixi, Heilongjiang Province was suspected of food poisoning, 7 people died and 2 people were still being rescued. Poisoning is caused by eating homemade sour soup, and the food ingredients have been frozen for one year. This incident was due to the serious exceeding of the standard of aflatoxin in food, which was initially determined as aflatoxin. However, a day later, the situation reversed. Not only did the death toll rise to eight, but the culprit also changed from "aflatoxin" to rice fermented acid.
What are aflatoxin and Aspergillus oryzae acid?
Aflatoxin is a metabolite produced by Aspergillus flavus and Aspergillus parasiticus. Among them, 30%-60% of Aspergillus flavus strains can produce aflatoxin, which is easy to breed in food, oil crops and dried fruits, and can also be contaminated by Aspergillus flavus in meat and dairy products. Aflatoxin is very toxic and is one of the strongest carcinogens known at present. In China, 10% of liver cancer may be related to aflatoxin pollution. Aflatoxin is very heat-resistant and can only inactivate most of it under the action of high temperature (100℃) for a long time. Therefore, the harm of aflatoxin is very great.
Rice yeast acid is a toxin produced by Pseudomonas cocoanum under certain conditions, and it is the main cause of poisoning caused by fermented corn flour products, deteriorated fresh tremella and other deteriorated starch products. This toxin will cause serious damage to human heart, brain, liver, kidney and other important organs, and this damage is often irreversible. After poisoning, symptoms such as nausea, vomiting and diarrhea will appear in clinic, and even severe cases will die of shock, with acute onset. Generally, the incubation period is 30 minutes to 12 hours, and very few are 1 to 2 days. At present, there are no special detoxification drugs in medicine. Once poisoned, the mortality rate is as high as 40%. In addition, this toxin is extremely heat-resistant, and high temperature treatment cannot reduce its toxicity.
What other toxins are more likely to be eaten by mistake?
At present, there are more than 200 known mycotoxins, but the toxins causing food safety incidents are reported to be more and more toxic. In addition to the two mentioned above, they also include ochratoxin produced by Aspergillus and Penicillium, zearalenone produced by Fusarium and fumonisin produced by Fusarium. Due to the growth characteristics of mold, these mycotoxins mainly pollute cereal products, such as corn, wheat, rice, barley, millet and oats.
In the routine food microbial detection project, the main targets of pathogenic bacteria detection project are Salmonella, Staphylococcus aureus and Shigella in food safety hazards, which will produce corresponding bacterial toxoids, namely Salmonella toxin, Staphylococcus enterotoxin and Shigella dysenteriae toxin. In addition, in March this year, four people died and 30 people were hospitalized in the United States, which was caused by Listeria, which can produce listeriolysin. These four toxins are the most likely bacterial antibiotics in our lives.
The biggest way for human beings to ingest toxins is to eat food contaminated with toxins. Usually it goes through three links: first, food is contaminated by pathogenic microorganisms during transportation, storage and sales; Second, improper food storage methods, contaminated food in suitable growth conditions, pathogenic microorganisms multiply, produce toxins or store at low temperature for a long time, leading to toxin accumulation; Third, improper cooking and processing of food, undercooked or inadequately cooked contaminated food, lead to the residue of pathogenic microorganisms and toxins. Finally, eating these foods led to poisoning.
Is there a risk of spoilage in frozen food?
Refrigeration at 4℃ and freezing at-18℃ are the general set temperatures of household refrigerators, which are also the best conditions confirmed by science. But many people regard the refrigerator as a universal storage box, especially the freezer. People think that things will never go bad as long as they are kept in the refrigerator, so it is not uncommon for many families to freeze food in the refrigerator for half a year or even a year. There are still many people who always like to stuff the refrigerator full. When they find that the food has expired, they are reluctant to throw it away, thinking that it will not expire if it is frozen. This is obviously a big mistake.
Frozen food also has the risk of spoilage. Although low temperature can inhibit the growth and reproduction of microorganisms, it can not completely kill microorganisms, so many microorganisms can still grow slowly at low temperature. Once food is contaminated by pathogenic microorganisms, toxins will still accumulate over time.
What should I pay attention to in daily food preservation?
Food should not be stored for too long in daily preservation. It is best to finish the prepared food as soon as possible. The refrigerator is not a safe, and bacteria will still breed. Don't store the food you eat directly in the refrigerator for too long. Processed food should be thoroughly cooked to completely kill bacteria. Food stored in the refrigerator must be thoroughly heated before it can be eaten; Raw and cooked foods should be separated to reduce cross-contamination; Try to seal and preserve food to avoid pollution; Try to eat food once after thawing, and don't freeze it again. Moldy food should be thrown away in time, and must not be washed and fished out to continue eating; Raw fruits and vegetables should be thoroughly washed with running water before eating.
Nowadays, the circulation of fresh food is very developed, and there is no need to store a lot of food in the refrigerator for a long time. Try to buy and eat fresh food and use it to protect our health.