Some time ago, there was a hot news about food safety. There was a sentence in it: “Although vacuum packaging was carried out, but because there was no product-related information marked, the buyer reported it as a ‘three-no’ product and went to court.” Whether it is Producers, claimants, courts, media, and the majority of netizens probably think that “vacuum packaging” can ensure safety, so they all focus on “not labeling product-related information”. But the truth is different from what everyone thinks: if the food is not refrigerated or frozen after vacuum packaging, it is more dangerous than if it is not vacuumed.
Vacuum packaging only inhibits “aerobic bacteria”
Vacuum packaging is a “modified atmosphere preservation” process. The purpose of vacuuming is to eliminate the oxygen in the food, because the deterioration of food is closely related to oxygen. On the one hand, fats and oils will oxidize in an aerobic environment, resulting in a bitter taste; on the other hand, aerobic bacteria in food will grow up, causing food to spoil, sour, smelly, and sticky.
Vacuuming removes oxygen, oil oxidation is inhibited, the growth of aerobic bacteria is also inhibited, and food can remain “unchanged” for a longer period of time. However, this “unchanged” is only visual and olfactory.
Nature is full of various bacteria. When there is oxygen, aerobic bacteria can flourish, while anaerobic bacteria are inhibited; after vacuuming, aerobic bacteria are inhibited, and anaerobic bacteria are at ease. The growth of anaerobic bacteria does not make food sour, smelly, or sticky, but it can produce toxins. The most important of these is Clostridium botulinum, commonly known as “botulism”.
Botulism exists widely in nature, such as vegetables, fish, and poultry. It’s not very dangerous or hardy on its own, and normal cooking (cooking food by steaming) is enough to kill them. Its scary thing is its ability to form spores. Spores are very tenacious and can persist in boiling water for several hours under neutral conditions. When the conditions are right, that is, “normal temperature, not enough preservatives, non-acidic”, they can grow and produce botulinum toxin. Botulinum toxin is one of the most toxic biological toxins, with lethal doses on the order of micrograms.
Vacuum packaging at room temperature just “doesn’t look bad”
As mentioned earlier, general cooking can kill botulism bacteria, but not spores. For example, at 100°C, it takes 5 hours to kill the spores. So, remember this knowledge point: there may be spores of botulism in your cooked food.
At this time, if you perform these treatments on them:
1. Eat them directly, then these spores will not cause problems; 2. Put them in the refrigerator, because the temperature is low, these spores will not grow up, and they will No toxins will be produced; 3. Put it at room temperature, because there is oxygen, these spores will not grow up and produce toxins, but the food may be spoiled by other bacteria; 4. Put them in vacuum packaging at room temperature, These spores grow into botulism bacteria, which secrete the toxin, while the aerobic bacteria do not grow, so the food “looks okay”. If you eat it, you may suffer from dizziness, weakness, and blurred vision in mild cases, and in severe cases, you may be admitted to the hospital.
“Normal temperature, no oxygen, no preservatives”: the onset conditions of botulism
Botulinum toxin is widespread, and botulinum toxin is also very poisonous, but there are not many actual cases of poisoning. The reason is that most people cook at home or eat in restaurants, most of which are cooked and eaten immediately, which will not give room for the growth of botulism; in industrial production, as long as the regulations are followed or certain processing techniques are adopted, it is not difficult to avoid.
However, in many small shops such as “private food” and “farm food”, the production process and environment are difficult to guarantee. If these foods are cooked and eaten now, there will be no botulism; however, if the cooked food is vacuum-packed and then sent through logistics, it meets the conditions for the onset of botulism of “normal temperature, oxygen-free, and preservative-free” ——Whether you will be recruited or not, you can only leave it to luck.
Simply put, vacuum packaging deli food makes sense—a vacuum better preserves its flavor and texture. However, after vacuuming, refrigeration is required, otherwise the safety risk will be higher.
