On the short video platform, you can see such a video from time to time: the beef bought by netizens home, after cutting, keeps jumping or shaking.
So some people are worried, is this a parasite? Can the throbbing beef still be eaten?
Beef will move 丨 video GIF
In such a situation, you don't have to worry too much. Beef beating often means that it is fresh and can be eaten. However, to buy really delicious meat, it is not necessarily possible to rely on freshness alone, and the subsequent treatment of meat and meat quality are also reference items.
Beef beating?
The phenomenon of "beef moving" is not uncommon, and it has attracted attention on social media dating back to at least 2015. At that time, the beef bought by Ms. Cheng of Jining, Shandong Province, did not stop shaking, and she took pictures of it with her mobile phone in time.
People don't dare to eat throbbing beef. 丨 News screenshot
At that time, Shandong Satellite TV reported on the incident and consulted Inspector Lu Suwen of the Animal Health Inspection Institute in Lixia District, Jinan City, about Ms. Cheng's video.
At that time, Shandong Satellite TV reported on the matter. 丨 News screenshot
For this phenomenon, Inspector Lu Suwen gave a clear explanation: the slaughter time of this piece of meat is relatively short, the central nervous system of the animal has died, but the nerve endings around or inside the muscles have not died and are still beating. This situation is no problem to leave it for a while.
During the interview, the reporter also asked whether there would be illegal traders who would create the illusion of beating through some means. Inspector Lu said: "Based on my many years of experience, I have not found this situation, and there is no drug or other way to cause muscle tremors. ”
In short, it is a transient state of muscle when the animal has just died.
Theoretically, all kinds of animals will have such a transition time after death. However, the "tremor of cut flesh" seen in reality basically occurs on beef and is not seen in other animal meats. This may be because the cattle are larger, and the peripheral nerves can remain active for a longer time after the central nervous system dies.
The freshest meat, not necessarily the best
In general, we would like meat as fresh as possible. But in terms of taste, the freshest meat that has just been slaughtered is not the best taste.
Before the animal is slaughtered, the cells in the body are constantly metabolizing. After slaughter, different life activities do not have the same rhythm of termination, and some biochemical reactions continue, which affect the "quality" of the meat in several ways.
First, there is some collagen and elastin in the muscles that entangle muscle cells together. The longer the animal grows, the more strong these proteins are, the more tightly connected they are, and the "older" the meat becomes. After the animal dies, these proteins slowly degrade, making the meat "tender."
Second, some enzymes break down certain proteins into individual amino acids or polypeptides composed of several amino acids. And certain amino acids produce the "flavor" of meat.
Third, some fats oxidize. Originally, fat oxidation is something that food should avoid, but the proper oxidation of meat will bring a different flavor from fresh meat, and this flavor will be liked by many people.
This process of making the meat change appropriately is known as "post-cooked processing" and is an important area of the meat industry. For example, high-grade steaks have to be "dried and cooked" - after slaughter, large pieces of meat are quickly reduced to refrigeration temperature, hung up for a week or even half a month, and finally the surface meat has dried and is difficult to eat, and the steak only takes the inside part. The beef treated in this way is not only tender but also has a unique flavor, high-quality, and the price is naturally very high-end.
The acidity of meat changes over time
Normally, animals' muscles contain a lot of glycogen. After the animal is slaughtered, glycogen is slowly converted to lactic acid, and the pH of the meat slowly drops, and after 24 hours, it will drop below the pH of 6.2. These lactic acids soften the meat, increase flavor, and have a certain bacteriostatic effect.
Normal meat, here's what:
Normal Meat Meat Reference 1
However, if pigs are frightened before slaughter, or are under a lot of stress due to other factors, they will secrete a lot of adrenaline, causing glycogen to break down rapidly. After slaughter, lactic acid will form rapidly, and too much lactic acid will make the meat white and extremely soft. The pH of such meat can drop to between 5.4 and 5.6 after 24 hours, which is called PSE meat.
Such meat is neither good-looking nor tasty, and the typical PSE meat is as follows:
PSE Meat Meat Reference 1
If the large amount of glycogen decomposition does not occur near slaughter, but lasts for a long time, the resulting lactic acid may be metabolized in advance. At this time, there is very little glycogen after slaughter, and there is not much lactic acid in conversion, and the pH value cannot be fully reduced. After 24 hours, the pH may still be between 6.4 and 6.8. This meat is dull in color, hard and dry, and is called DFD meat.
DFD meat is also neither good-looking nor tasty, and the typical color is as follows:
DFD Meat Reference 1
In reality, pork is more likely to appear PSE meat, while beef and mutton are more likely to appear DFD meat.
In order to avoid the appearance of PSE meat, pigs should be as happy as possible before slaughter, do not get hurt or be frightened. The FAO's recommendation is to allow pigs to rest quietly 24 hours before slaughter, thereby retaining as much glycogen as possible in the muscles.
The color of the meat also changes during storage
The color of the meat mentioned earlier refers to the color within 24 hours of slaughter. And during longer storage, the color of normal muscles also changes.
The color of beef is mainly determined by the myoglobin in it. Myoglobin comes into contact with air and combines with oxygen to form oxytropin, and the meat shows a bright red color.
The color of oxygenated myoglobin 丨 Pixabay
This reaction is reversible. In low-oxygen environments, such as in vacuum bags, oxygenated myoglobin will turn dark purple due to the loss of oxygen; however, when opened, they will combine with oxygen and quickly return to a bright red color.
Bright red is what consumers like. However, in prolonged contact with air and under indoor light exposure, oxygenated myoglobin will oxidize to form methemoglobin. The methemoglobin is brown, and the beef loses its pleasing red color.
On the right is the color of methemoglobin 丨 smokedbbqsource.com
Many fresh meats sold in supermarkets now are filled with a specific composition of oxygen and carbon dioxide mixed gas in the packaging box, which can not only inhibit the growth of bacteria, but also prevent oxygenated myoglobin from being converted into high iron myoglobin, thereby maintaining the bright color of the meat. This technique is known as "modified atmosphere preservation".
In short, meat selection is a science, I hope that everyone can eat delicious and safe meat.
bibliography
1.D. Dave, A.E. Ghaly.Meat Spoilage Mechanisms and Preservation Techniques: A Critical Review. American Journal of Agricultural and Biological Science.6(4):486-510,2011
Author: Yun Wuxin
Edit: Li Xiaoqiu
Source: Fruit Husk
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