In modern families, frozen meat is commonly found in refrigerators. Many people like to buy large quantities of meat at once and freeze them so that they can be easily accessed at any time later.
However, many people are still a little hesitant and confused about the safety and shelf life of frozen meat, especially worried about whether long-term consumption of frozen meat will increase the risk of cancer. So, let's take a look at how frozen meat is preserved.
The principle of preservation of frozen meat
Freezing technology is a major contributor to modern food preservation, as it increases the shelf life of foods by lowering their temperature and refrigerating them.
In the freezer layer of the refrigerator, the temperature is usually maintained below -18°C, which effectively prevents the growth of microorganisms and allows them to go into a dormant state.
However, this does not mean that the microbes have been completely dried out, and once the frozen food has thawed to room temperature, it is possible for the little ones to be active again. Therefore, freezing is mainly to prolong the shelf life of food.
As the freezing time increases, the fat and protein in the meat may slowly oxidize. Fat oxidation can give meat a bad smell and may also produce some harmful things.
Oxidation of proteins can lead to the loss of some important nutrients in meat. In addition, vitamins, which are important for our metabolism, may also be reduced during the freezing process.
The preservation principle of frozen meat is actually to inhibit the growth of microorganisms by low temperature. But remember, once the meat has been thawed, it should be disposed of quickly, and it should not be left at room temperature for too long, otherwise the quality will be compromised.
As for the carcinogenic risk
At present, there is insufficient scientific evidence on whether properly stored and handled frozen meat increases the risk of cancer.
Theoretically, under the right conditions, the low temperature environment can effectively inhibit the growth of microorganisms, so the consumption of frozen meat does not pose a carcinogenic threat to health.
However, in real life, the conditions under which home refrigerators are used are often difficult to meet the standards of sterility, safety, and hygiene, which may have an impact on the preservation quality of food.
Household refrigerators often turn on and off or experience power outages, which will affect the temperature stability of the refrigerator, which in turn affects the preservation quality of food.
Meat that has been frozen for a long time may undergo oxidation, leading to an increase in free radicals in it, which may contribute to the body's aging process.
In addition, oxidized cholesterol may cause damage to the endothelium of blood vessels, which can easily promote the occurrence of arteriosclerosis, bringing some potential health threats to the body.
Although it is theoretically possible to preserve meat at low temperatures does not increase the risk of cancer, in practice, we still need to be cautious.
Even if frozen meat is completely hygienic and safe, it is difficult to meet the standards of sterility, safety and hygiene in the true sense. Therefore, we should choose ingredients reasonably and pay attention to the preservation time according to the actual situation to ensure the freshness and safety of the food.
We should also be aware of the problem that long-term storage of frozen meat is not recommended for long-term consumption. Long-term freezing can lead to the loss of nutrients in meat, which may affect its taste and texture.
Even though frozen meat can be stored for a long time under the right conditions, it is recommended to consume it as early as possible and avoid long-term storage in order to ensure the quality and nutrition of the food.
Repeated thawing and refreezing of meat should be avoided
The moisture in the meat forms ice crystals during the freezing process, which increase as the temperature decreases. These ice crystals can expand and disrupt the cellular structure of the meat, causing the connections between cells to break.
When the meat is thawed again, these broken cells are unable to retain moisture effectively, resulting in a loss of juice, which in turn affects the taste and nutritional value of the meat.
Studies have shown that repeated freeze-thaw cycles of meat can lead to a decrease in its water retention and a decrease in protein and vitamin content.
The microbial activity of meat after thawing is also a matter of concern. Freezing inhibits the growth of bacteria, but it doesn't kill them completely.
Once the meat is thawed, the bacteria that were otherwise suppressed begin to multiply. If the meat is thawed at room temperature, the bacteria will multiply faster.
Repeatedly thawed meat, the number of bacteria inside it can quickly increase beyond safe standards, increasing the risk of food poisoning.
Scientific studies support these ideas, confirming the nutritional and safety effects of repeated thawing and refreezing of meat.
CCTV Finance's "Is It Real" column once did a super interesting experiment! They took a piece of fresh meat, and then in just 5 days, it was repeatedly frozen and thawed 4 times!
Then after each thaw, they took samples to see if there was any change.
Guess what? After four rounds of freezing and thawing, the total number of colonies in this piece of "fresh meat" turned out to be 15 times that of the original!
Another study found that with the increase of freeze-thaw times, the hardness and adhesion of lamb increased significantly, while the stickiness, elasticity and cohesion decreased significantly.
Moreover, the color of the meat was also affected, with a significant decrease in redness, while the change in brightness and yellowness was not very noticeable.
The results of these experiments tell us that repeated freeze-thaw cycles have a significant impact on the quality of meat! With the increase of freeze-thaw times, the processing performance of meat will decrease, protein oxidation will intensify, and eventually the color and texture of meat will decline.
So, how should we properly handle meat? When buying meat at home, we should cut it into small pieces as needed, pack them separately and freeze them, so as to avoid repeated thawing of the whole meat.
When thawing meat, it should be thawed in a refrigerator or in cold water to avoid prolonged exposure at room temperature to reduce the chance of bacteria multiplying. Defrosted meat should be cooked as soon as possible to avoid re-freezing.
About the shelf life of frozen meat
Different types of meat have their own recommended shelf life when cryopreserved, which is based on the quality preservation and nutritional value of the food in the frozen state.
Let's talk about red meats, such as pork and beef. Due to its compact muscle fiber structure and moderate fat content, these meats can better maintain their quality and nutritional value in the frozen state.
Scientific studies have shown that red meat can last for 6 to 12 months when frozen.
During this time, the color, taste and nutritional content of meat do not change much, but beyond this time frame, meat may experience fat oxidation and protein degradation, affecting the flavor and nutritional value of the food.
Next, let's talk about poultry meat, such as chicken and duck. These poultry meats are high in unsaturated fatty acids, which makes them more susceptible to fat oxidation during freezing.
The recommended cryopreservation period for poultry meat is usually 6 to 10 months. During this period, poultry meat retains its quality and nutritional value. However, if the recommended period is exceeded, the rate of fat oxidation of poultry meat will accelerate, resulting in a decrease in food quality.
Finally, let's talk about seafood, especially fish and shellfish. These foods are rich in polyunsaturated fatty acids, which are very beneficial to human health, but also make seafood more susceptible to oxidation when frozen and stored.
Seafood has a relatively short shelf life, and it is generally recommended to consume it within 3 to 6 months. Beyond this time period, the quality and nutritional value of seafood will decline rapidly, especially the oxidation of fatty acids will lead to the odor of food.
In fact, scientists have determined the optimal freezer life for different types of food by studying the physical and chemical changes during the freezing process.
These studies include monitoring of the rate of oxidation of proteins and fats in foods, microbial activity, and changes in the sensory quality of foods.
In practice, the cryopreservation period is also affected by factors such as freezing conditions, packaging materials, and how it is handled before freezing.
The use of vacuum packaging or modified atmosphere packaging can reduce the contact between food and air, thereby extending the frozen shelf life of food. Proper handling of food products before freezing, such as pre-cooling, rinsing, and pickling, can also improve the freezing and preservation of food products.
Therefore, if you want to enjoy fresh and delicious meat and seafood, you must not only choose the right frozen storage period, but also pay attention to the freezing conditions and processing methods.
Potential risks that may exist in meat
In addition to carcinogenic concerns, frozen meat can also be affected by other contaminants, such as heavy metals, hormone residues, etc.
Heavy metal pollution, such as lead, cadmium and mercury, is not a good thing, and is an adjunct to industrial activities and agricultural fertilizers.
You're welcome, but once in our bodies, they become stubborn "tenants" who prefer to hide in their livers and kidneys.
Eating food contaminated with heavy metals for a long time is not good, it can cause a lot of problems to our body, such as damaging the nervous system, messing up kidney function, suppressing the immune system, and may even cause cancer!
Next, let's talk about hormone residues, which are mainly from growth hormone and other drugs used in animal husbandry. These things are mainly used to promote the growth of animals and produce more meat.
But the problem is that these drugs can remain in the meat and then be eaten by us. Consuming meat containing hormone residues for a long time is not fun, it will affect our endocrine system, and cause us to stunt growth and fertility problems!
Don't think that these problems are just a matter of individual people, food safety is related to the health of each of us, and even related to the public health of the whole society and the country's economy.
References are as follows:
[1] Study on the effects of freezing and thawing on meat quality
[2] Freezing of meat and aquatic foods: potential mechanisms and effects of protein oxidation
[3] Study on the effect of repeated freeze-thaw on protein oxidation and quality of mutton