How much nutritional value does frozen food retain?

Frozen meat is definitely much lower than fresh meat, and if frozen meat is properly processed, nutrients will certainly not be lost. Most people choose the best fresh meat because they think that frozen meat is not nutritious and tastes bad, is frozen meat really like this??? Jiang Zhuoqin, professor and doctoral supervisor of the Department of Nutrition at the School of Public Health of Sun Yat-sen University, and Yang Guanfeng, president of the Guangdong Food Culture Research Association, believe that the main reason why people prefer fresh meat and are reluctant to buy frozen meat is consumption habits and consumer misunderstandings.

Experts believe that the main reason why people prefer fresh meat and are reluctant to buy frozen meat is consumption habits and consumption misunderstandings. Americans buy frozen meat when they buy beef, and even if they buy fresh beef, they have to put it in the freezer and freeze it in a -18 environment for about a week before they take it out for consumption, and high-end steaks are also processed in this way. According to scientific analysis, beef freezing-18 for a week is to completely sterilize and deacidify, and the muscle fibers of the steak after deacidification are degraded, and the meat becomes more tender.

Experts have summarized the four main benefits of eating frozen meat:

1. More hygienic From the perspective of hygiene, freshly slaughtered meat often contains various bacteria, and there may even be some viruses, such as porcine yellow bile virus, which is hidden in bones, blood and muscles; The bacteria in the frozen meat have been excreted or frozen to death.

Second, fresher pigs, cattle and sheep and so on slaughtering the fastest 2 3 hours into the quick-freezing process, home after more than 1 hour of thawing, meat exposure time in room temperature is only about four or five hours, and fresh meat is generally transported from the slaughterhouse at more than 4 o'clock in the morning, sold in the meat stall, to the public's table at the fastest to 11 o'clock at noon, meat exposure time in room temperature and air for more than 6 hours.

3. More delicious From the perspective of meat quality, fresh meat has a strong sour taste and juicy, so it needs to be sour. Livestock and poultry all need a process of acid removal after death, so both fish and chicken also need to be deacidified. Acid excretion is a kind of natural degradation, the method of timely freezing plays a role in its natural degradation, about 3 hours later, the meat will enter the autolysis period, the meat quality begins to become soft and umami, 24 hours after eating will taste more delicious.

Fourth, nutritious Compared with fresh meat, there is not much difference in nutrition, but frozen meat needs to be thawed when eating, and improper thawing methods will cause the loss of nutrients. As long as it is properly thawed and consumed reasonably, the nutritional value of frozen meat is not lower than that of fresh meat. Eating frozen meat is safer than eating fresh meat.

For quick-frozen food, people always have concerns that it is not fresh enough and not nutritious. In fact, from a nutritional point of view, "quick-frozen" can maintain the original freshness, color, flavor and nutritional content of natural foods to the greatest extent. Especially for people who are busy at work, instead of buying fresh meat and vegetables that they need for the week at home and piling them in the refrigerator at one time, it is better to use quick-frozen food instead.

This is because it takes at least a few hours to freeze food in the household refrigerator, while the real quick-frozen food is to achieve the freezing effect within 15 to 30 minutes, so that the molecular structure of the food is basically unchanged, and it will not cause nutrient loss like "slow freezing". Theoretically speaking, there is not much difference in nutritional value between quick-frozen dumplings and freshly packed dumplings, because the nutrient molecules and water molecules in the food can remain unchanged under quick-frozen conditions.

Frozen food is healthy, and the nutritional value of the food has not been lost. The water and juice in the tissues of the food will not be lost, and the original taste of the food can be preserved to the greatest extent. Moreover, at such low temperatures, microorganisms will not multiply, and food can be stored for a long time.

Meat is sold to provide protein and minerals. In a very low temperature environment, the protein and mineral content of meat does not change, so the nutritional value of quick-frozen meat is not lower than that of fresh meat cavity grinding. Frozen fruits and vegetables are quickly frozen at 18 years old.

At this temperature, the respiration of fruits and vegetables is almost stagnant, and microorganisms and bacteria cannot grow and reproduce. Therefore, the nutritional value of quick-frozen fruits and vegetables will not be worse than that of fresh fruits and vegetables.

Frozen food nutrition will definitely be lost.

The source of the calendar is hail.

Frozen food also has a shelf life. The length of the period depends on the type of food, pre-freezing treatment and freezer temperature conditions.

Pre-treatment has a great impact on the shelf life of frozen foods. For example, fresh fish is frozen without any treatment and can only be stored for 1-2 months; However, after scientific treatment and then frozen, the shelf life can be extended to half a year. According to Professor Chen, poultry, seafood, and river fresh should be eviscerated, washed inside and out, and then frozen; Other foods and meats also need to be carefully washed before freezing to remove bacteria from the surface.

In addition, all food should be divided into one-time portions and carefully packed in plastic wrap bags or plastic wrap before being placed in the freezer to prevent moisture loss. It's a good idea to label the outer packaging with the date and name so that it can be picked up later.

Secondly, the quality of the refrigerator and our daily usage habits also have a great impact on the shelf life of food. When buying a refrigerator, you should find out the refrigeration performance, and the temperature of the freezer compartment should reach below minus 18. Nowadays, some products can reach minus 20 - minus 23, which is more conducive to extending the shelf life.

In addition to keeping the temperature cold enough, it is also important to maintain a stable temperature, as fluctuations in temperature can cause cell breakdown, resulting in nutrient loss. Therefore, when taking food, you should try to take it as quickly as possible, take it all at once, reduce the time and frequency of opening the refrigerator, and be careful not to lose power frequently; Processed food must be cooled before freezing; It is better not to freeze the food again after thawing.

According to the above methods of scientific freezing, how long can different foods be preserved?

Red meat: mainly includes pork, beef, mutton, etc. The shelf life is 10-12 months. Among them, beef is more stable than pig and mutton, and lean meat is preserved longer than fatty meat.

Poultry: chicken, duck, goose, pigeon, etc. The shelf life is slightly shorter than that of red meat, at 8-10 months.

Seafood, river fresh: including fish, shrimp, turtles, shellfish, etc. Because they contain a large amount of unsaturated fatty acids that are easy to oxidize, the shelf life is shorter than that of livestock and poultry meat, generally up to about half a year, and it is best to eat within 4 months.

Vegetables: Generally speaking, green leafy vegetables, melons and fruits cannot be frozen. However, a small number of vegetables, such as corn, chestnuts, beans, etc., can be frozen and kept fresh.

However, due to the decomposition of chlorophyllase, peas, broad beans, green beans, etc. can only remain fresh and green for about 2 months, and although the taste and nutrients will not change significantly if they continue to be preserved, the color will turn from green to yellow, affecting the appearance. Corn, chestnuts, etc. do not have this problem, and can be stored for about 5 months.

Quick-frozen staple foods: such as dumplings, buns, glutinous rice balls, wontons, etc. Because the texture of the filling with complex ingredients will gradually change under low temperature conditions, and it is also easy to carry over the flavor, it is not advisable to freeze it for too long, and it is best to eat it within one or two months.

How long does this frozen food have to be frozen? This tung high depends on the attributes of your food. If we have our own home, it may be frozen for as long as possible, but if the cruise ship land is like a factory, he will definitely have a standard. He'll do it to that standard.