In the face of a food that has not deteriorated for a long time, everyone's first reaction is often "definitely added a lot of preservatives". This concept makes mothers all over the world very resolute in their attitude towards canned food and instant noodles: there are no unjust, false and wrongly decided cases of all executions. But is it true that the longer the shelf life of a food, the more preservatives there are?
The burger in the picture was kept in a shoe box for 24 years without decay. This has led many netizens to question the large amount of preservatives contained in it, and some people even jumped at the prophet: as long as McDonald's eats enough, you can get eternal life. I have to say that everyone has a lot of personality and ideas and is generally very spiritual.
In fact, to understand this problem, we must first know why food spoils. There are a large number of microorganisms in our daily environment, and when the nutrients, moisture, temperature and acidity of food are just right for microbial reproduction, they will multiply in large quantities after a period of growth and produce a series of harmful substances that spoil other foods.
In this way, the core of antiseptics is actually to suppress the excessive reproduction of microorganisms in food. For example, preservatives can inhibit the growth of microorganisms by destroying their growth conditions, or directly destroying the microbial body. However, it is not that the longer the shelf life of the food, the more preservatives, because such as high temperature sterilization, dry dehydration, high osmotic pressure environment can extend the shelf life of food.
As far as the hamburger is concerned, it is likely that the heat treatment before the sale controls the microorganisms in the ingredients at a low level, while the storage environment is relatively dry, the shoe box is relatively closed, and when the food and environment are dry enough, the microorganisms cannot grow. Moreover, McDonald's beef patties and fries are quick-frozen ingredients, cold chain transportation, and are sold and eaten immediately after processing in the store, and there is no need to add preservatives to increase costs. Of course, these are the replies given by McDonald's officials, and you are right.
In fact, it is not difficult to see that the so-called "natural preservatives" can basically be summarized as "high salt, high sugar, and lack of water". For example, honey, its main components are glucose and fructose, there is very little water, microorganisms due to the relationship between osmotic pressure will lose a lot of water and lose activity. There is also yogurt that does not need to add preservatives, because it contains a large number of lactic acid bacteria, and other bacteria are difficult to survive. But if you leave it too long, the lactic acid bacteria are dead, and other microorganisms will take advantage of it.
There are also dried foods such as dried and dried turnips, dried sweet potatoes, bacon, sausages and other dried foods, which lack the moisture required for microbial growth and reproduction.
The instant noodles that were often sprayed on the news before are also experts in this aspect of technology, first of all, its noodles, whether fried or non-fried, have a very low moisture content, such as a master's noodles with a moisture content of less than 3%. The national standard stipulates that foods with a water content of less than 8% do not need to add preservatives. Look at the vegetable buns, powder buns, are dehydrated and high-salt, although there is water in the sauce buns, it is also high salt, high oil.
However, there are some wet vegetable packages such as sauerkraut, and the pickled ginger inside already has sodium metabisulfite before the manufacturer buys it, but according to the regulations, it can be marked without labeling, and it is also within the safe range.
Let's talk about the difficult brother of instant noodles - canned. During the epidemic, many supermarkets in Europe and the United States have sold out canned food. A few years ago, Costco also launched a special "doomsday survival canning" set, enough for 4 adults to eat for a year, and the shelf life is as long as 25 to 30 years, I can imagine my mother's disgusted face after seeing this news.
Because in China, canned food has long been synonymous with "no nutrition, unhealthy, preservatives", of course, Northeast people and canned yellow peach must be locked.
In fact, canned fruits such as yellow peaches are not allowed to add any preservatives according to national regulations. Its high-sugar, anaerobic environment is not suitable for microbial growth, so as long as the sterilization is thorough, there is no need to add preservatives.
Canned meat is a little more complicated and may contain some anaerobic microorganisms, so the national standard stipulates that some additives (streptococcus lactate, sodium nitrite, potassium nitrite) can be used. Many processed meat products, such as ham and lunch meat, add sodium nitrite to the production. An important reason is to inhibit the growth of Clostridium botulinum. If the food is contaminated with this bacterium, botulism may occur after people eat it.
In the same way, there are cosmetics and eye drops, the addition of preservatives is to inhibit the growth of microorganisms, to ensure the safety of cosmetics, only meet the standards can be sold, otherwise it will soon deteriorate, and it will be changed in a few days. Generally, eye drops without preservatives, capsules, ampoules and other skin care products are small doses, fully sealed packaging, and must be used up in a short period of time after opening.
Back to the nutritional problems of canned food, in the process of high temperature sterilization, some vitamins and dietary fiber and other nutrients will indeed be destroyed, but can not say that it is "completely unnutrient", according to the USDA statistics show that water-immersed tuna contains no less nutrients than fresh tuna, which is rich in protein and minerals, but also rich in Ω-3 unsaturated fatty acids. Those nutrients that are usually lost are also easily replenished by other foods.
In fact, as long as the preservative is used legally and compliantly, if it is added according to the limit, it will not have any impact on the body. Because it has become a legal additive, it is done in a series of toxicological experiments, determined that in the case of limited addition, it is safe and harmless to the human body, and it can finally be approved for addition into food. Therefore, everyone does not have to "talk about decay and discoloration". Besides, they all eat life-saving food, do I still care about such a little preservative?