What kind of food should be stored in the Blast Freezer Cold Room?
What kind of food should be stored in the Blast Freezer Cold Room?
A few days ago, I talked about the refrigerator's Blast Freezer Cold Room, so what kind of food should be put into the Blast Freezer Cold Room?
A friend said: my family's blast freezer cold room is freezing last year's unfinished mooncakes It is estimated that they will not be thrown away until the Mid Autumn Festival next year, and then a batch of moon cakes will be put in. Another friend said: it's still freezing the meat and chicken from the unit six months ago. Another friend said: there are a lot of frozen dumplings, stuffed with ice cream and ice cream and other cold drinks.
Why throw food into the blast freezer cold room? Can freezers really keep food forever?
Here we will focus on the basic principle of frozen preservation, and what is the effect of frozen food.
Stop the propagation of microorganisms, so that the food is not corrupt.
Under freezing conditions, the biggest benefit is that microorganisms cannot grow and reproduce. Even after long-term cryopreservation of some pathogenic microorganisms, the number of viable bacteria can be reduced. However, this does not mean that the microorganisms in the food raw materials will die completely in the blast freezer cold room. They are just no longer thriving and will not reach the level of food corruption.
So, not long ago, people heard that frozen dumplings contain a kind of pathogenic bacteria called Staphylococcus aureus, which is not surprising. Just last year, there was a serious food poisoning in Germany, which is said to be caused by frozen strawberries. This is another good proof that freezing will not completely freeze the bacteria to death. Quick-frozen food needs to be sterilized before eating to ensure safety.
Because microorganisms do not breed in the blast freezer cold room, many foods that are about to expire in the blast freezer cold room can be thrown into the blast freezer cold room if they are not expected to be eaten for the time being, before the microorganisms slowly propagate to cause corruption. What if we are going to have a meeting in another place tomorrow and the tofu we bought will reach the expiration date the day after tomorrow? The easiest way is to put it directly into the blast freezer cold room. Come back to eat frozen tofu, just after thawing, cut and boil. Cooked meat, cooked fish and so on can be preserved by freezing if they can't be eaten in a few days. Although the taste will be slightly worse after thawing, at least things will not be wasted.
2. Reduce the rate of the chemical reaction and prolong the shelf life of food.
In addition to microbial reproduction, there are many chemical reactions that make food quality worse. For example, fat oxidation can make fatty food produce an unpleasant smell, even unbearable "harass", or rancidity. For example, the color of food will change and gradually turn brown and black; the texture of the food will become less and less delicious in the storage process, and the fish and meat will become hard and firewood. At the same time, people are also concerned about the degradation of vitamins and health care ingredients in food during storage, and the health value is getting lower and lower.
When food is put into a blast freezer cold room at minus 18 degrees, the speed of many chemical reactions will be significantly reduced, that is to say, the change of food quality will be much slower than that at room temperature. Therefore, for those low moisture foods that can be stored at room temperature, putting them in the freezer can significantly extend the shelf life of them.
For example, a friend went to a famous tea production area to buy a lot of high-grade tea, which he could not drink for half a year but would lose its fragrance if he kept it for a long time, so he could divide it into small bags, tightly wrap it with waterproof packaging, and then put it into the blast freezer cold room. In this way, the next year out to drink, the taste is still fresh as before. In addition to tea, health products and some rare medicinal materials are also suitable for storage in the blast freezer cold room if they can not be used up temporarily.
However, for those foods with high moisture content, the effect of freezing on food preservation is closely related to the speed and temperature of freezing. Although lowering the temperature can reduce the speed of chemical reaction and help to preserve, freezing is not a good thing.
Water is a wonderful substance. When it freezes, its proportion drops from 1.00 to 0.91, and its volume increases by 9%. In addition, the phase change heat of water is too high. When it freezes, it will release a lot of energy. It is very difficult to reduce the temperature from 1 ℃ to - 1 ℃. After freezing, because the ice crystal is sharp and the volume will increase, the cells will be punctured, resulting in the outflow of cell juice and soft texture after thawing.
Therefore, when freezing, it is necessary to pass the freezing process as soon as possible under very low ambient temperature and high-efficiency cooling, so that the water in the food can not form large ice crystals, but many small ice crystals, so as not to puncture the cells so that the juice loss and soft texture will not easily occur after the freezing. This is the meaning of "frozen food". No one wants to produce "slow frozen food" because its quality must be poor.
At the same time, during the freezing process, some water in the food does not freeze. This is because only pure water can form real ice crystals, but the food is not pure water, which has dissolved substances. The higher the concentration of solute in the water, the lower its freezing point, and the less likely it is to freeze - when it snows, it is necessary to sprinkle salt to melt snow, which is the reason. When the temperature drops below the freezing point, the pure water becomes ice, and the rest of the solute will condense so that the freezing point will drop and resist the freezing tenaciously. However, when the solutes in the water are crowded together, it is more likely to have various reactions and make the quality of food decline.
——Low temperature makes the chemical reaction speed decrease, but ice makes the chemical reaction speed increase. Which of these two processes is more powerful? It depends on how low the temperature is. If the temperature is particularly low, as low as - 18 degrees, the overall effect is to make the food more stable. However, if the food is stored under - several degrees, the effect of cooling is not enough to counteract the effect of freezing. As a result, the storage effect of the food is not as good as that in the zero degrees fresh-keeping refrigerator!
Therefore, it is necessary to adjust the freezer to a sufficiently low temperature, and it should not be overloaded or frosted, otherwise, the refrigeration effect will decline and the storage effect will become worse.
The method of freezing preservation is used to prevent all kinds of starches from drying and hardening.
It is known that all kinds of cooked staple foods will dry and harden in a period of time. No matter rice, steamed bread, noodles or cakes, this is the case. This is a process called "starch aging and regeneration". This process will happen at room temperature, but it will happen faster at the temperature of the cold storage room, so the steamed bread and cake will still harden when they are put in the cold storage room, and because the mold can withstand the cold storage temperature, it will grow mold after a long time. However, in the case of freezing, the process of aging and regeneration can hardly happen.
Frozen storage of all kinds of cooked pasta is a unique skill. Many people are greedy to buy one free and fast expired bread from the supermarket. If they can't eat a big bag of steamed bread rolls, they can pack small bags separately, and then freeze up. They are not afraid of the problem of expiration. Mould will never grow under freezing conditions. Take it out and thaw it in the microwave oven, soft and fresh as before! The heating time of defrosting is shorter than longer, and the final temperature of heating can reach room temperature. And it's better to thaw with packaging. Because it's heated to room temperature, you don't have to be afraid that plastic bags will break down and release toxic substances. The same goes for rice and steamed bread when they are taken out of the freezer.
Although it's not wrong to store mooncakes by freezing, it's a pity to put them in the refrigerator for a whole year and then throw away the old ones and put them into the new ones. It's better to take them to the community staff and the young and thin security guards before the festival!
4. It can prevent the growth of insects by frozen storage of dried grains, beans, and fruits for a period of time.
In summer, food, beans, nuts, dried fruits, etc. are easy to grow insects. Especially delicious raisins and dates, often grow some nasty meat worms. If they are divided into small bags that can be eaten at one time in advance and packed tightly, they will be put in the freezer for two or three weeks, the eggs naturally carried in the natural food will not germinate normally, and the sealed agricultural products will be stored for a longer time.
The freezer, like the freezer, must be separated from the raw and cooked, and from the meat and vegetable. And all food must be separately packed to avoid mutual contamination. The raw fish and meat in the freezer will carry a lot of bacteria, even a variety of pathogenic bacteria, so it is absolutely not allowed to mix with cooked food, frozen staple food, and cold drinks.
Here's how the freezer should store food:
Raw fish, raw meat, seafood, raw tofu, these raw foods that need to be fully heated can be placed in the lower layer.
2. All kinds of cooked pasta, pasta, and other starch staple foods, as well as all kinds of cold drinks, are put on the top.
3. All kinds of frozen products, such as frozen dumplings, frozen peas, frozen toon, frozen beans, frozen strawberry, and mulberry, are placed in the middle or upper layer together with the main frozen food. In any case, it must be separated from fish and seafood.
Finally, it should be pointed out that, like refrigerated rooms, refrigerated rooms need to be cleaned regularly. It is recommended to clean and wipe them once a month. Also, defrost. It is not allowed to distinguish the quick-frozen lattices that are raw and cooked. It is recommended to clean them every time they are used.
For high moisture food, long-term storage in the freezer will not corrupt, but long-term growth will also cause quality degradation, especially fat oxidation, poor protein texture, and reduced vitamin content. So, even if frozen food can be preserved for 12 months without corruption, it's better to eat it within two months. Otherwise, it's not worth spending the price of fresh food, eating nutritious food with the bad taste and a lot of electricity!