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Too long to look at
Colorful meat, in fact, there is no problem, to some extent may be more "fresh".
Two days ago, the editor took out two photos.
The raw meat on the left is pork, and the surface layer looks like a circle of beauty. The cooked meat on the right is lamb, and a rainbow appears on the surface.
These two pieces of meat... Is it broken?
Both photos are original Apple camera films, and the photo parameters have not been adjusted except for stitching.
The secret of "beauty meat" is hidden in the preservation technology
First, let's talk about "beautiful meat", the surface is powdery and tender, and the inside is the dark red color of pork that we are more familiar with.
Could it be that the black-hearted merchants have done something? Or is the quality inspection not passed, and the colleague just happened to encounter the polluted fish that slipped through the net?
First rule out the possibility of bacterial contamination
First of all, I ruled out the possibility of various germ pollution, first, because colleagues said that there was nothing unusual except for the color, and secondly, the level of this "beauty" was too uniform, not like germ pollution, but like contact with the air...
yes! Conan Daigo .jpg
Let me first finish the third point, that is, on the e-commerce platform that sells this product, one of the product display photos is like this...
The picture is from a photo of chilled pork products on an e-commerce APP.
Although the color gap between the surface and the inside of the product map is not as obvious as that of my colleague's photo due to lighting, filters and other reasons, it can still be seen that the color of the surface layer is more pink.
Extrapolating from common sense, this situation is highly probable a normal phenomenon.
Therefore, the possibility of staining, bacterial contamination, etc. is temporarily excluded.
But why does the surface of the meat become pink and tender?
Let's go on to the clue of "air."
The "gas" of preservation gives the meat a "beauty" by the way
I don't know if you have noticed, now the cold and fresh meat sold on the e-commerce platform, the packaging is full of "gas", the secret of "beauty meat" is in these "gas".
The picture is from a photo of the packaging of chilled pork on an e-commerce APP.
In fact, the color of meat has a far greater impact on consumers' desire to buy than other quality factors.
The color of the meat is determined by the chemical state of myoglobin. Normally, myoglobin first binds to oxygen to form bright red oxygenated myoglobin, which is then further oxidized to tan methemyoglobin by other factors.
When more than 40% of the meat surface is methemoglobin, the color of the meat is difficult to be accepted by consumers. [1]
The two pieces of flesh below were already a little tan in color.
Therefore, the inflatable modified air packaging technology has appeared, with O2, CO2, N2 and other protective mixed gases to replace the air in the packaging (can block the gas), to achieve the purpose of inhibiting the growth and reproduction of microorganisms, extending the shelf life of food, improving food preservation, has become one of the more popular meat color preservation technology in recent years.
Commercially available cold fresh meats are generally packaged in a complex atmosphere-modulated freshness package to maintain color and aroma. Studies in mainland China have found that the comprehensive effect of preserving fresh pork with 70% O2 + 25% CO2 + 5% N2 is the best, and the shelf life can reach 10 days.
High concentration of O2: inhibits the growth of anaerobic bacteria, and can also make meat and meat products bright red, prolonging the retention time of fresh color;
CO2: inhibits the propagation of aerobic bacteria and reduces the number of Pseudomonas fluorescentis, Listeria monocytogenes, etc.
However, oxygen penetration is limited, and even in a hyperomic environment, it will only form a stable oxygenated myoglobin on the surface.
Not only pork, beef, and lamb also use this preservation technology, of course, there will also be this phenomenon of superficial "beauty".
"Rainbow meat" is actually an optical phenomenon
I'm familiar with "rainbow meat" because I had this problem a few years ago.
The fresher, the more "rainbow"
When cutting meat, we usually cut the knife perpendicular to the texture of the meat, so that it tastes better.
When you cut a plate of marinated beef with this knife method, you may find rainbows or metallic lusters on several pieces of meat. This does not mean that the meat is spoiled and rotten or that there are any chemical additives, on the contrary, it may indicate that the meat is fresh.
Muscle is composed of countless muscle fibers, enlarge the muscle fibers, you will find that its structure is a section, this structure is called sarcomere.
When the muscle fibers are cut off, the broken muscle nodes form an orderly protrusion in the cross-section, similar to the diffraction grating, that is, through a specific regular structure, so that the appropriate light diffraction, interference, white light is decomposed into different spectra, on the surface of the flesh presents a mica-like luster, the same is true for the rainbow light on the back of CDs and DVDs. [3]
This is a metaphor of the times, do young people still use CDs and DVDs?
The muscle tissue of the pig's loin appears rainbow at a specific angle. Image from references[3]
If the meat is not fresh, the structure of muscle fibers, sarcomere and other structures may be destroyed by spoilage bacteria and cellular autolysin, and the rainbow cannot be seen.
Another possibility of forming "rainbow flesh" is membrane interference. The surface of the meat has a thin layer of oily fat, which affects the light that passes through it, so that only part of the color in the spectrum passes, and a rainbow will also appear. The gloss that occurs in this case is closer to the luster of a bubble or oil slick. [4]
Specific parts, cooked meat, and red meat are more common
The type of muscle tissue determines that only certain parts of the meat will appear "rainbow", such as beef is the semi-tendon muscle (starting from the root of the tail, extending from the back of the thigh down, ending in the shin of the calf a long muscle) is most likely to appear "rainbow", because the muscle fibers are uniformly distributed in thickness, and the cross-section is easier to form a regular grid, which is conducive to the occurrence of diffraction.
In cured and cooked meat, the muscle fibers are squeezed more tightly together, creating the mesh structure needed for diffraction.
In addition, pickled ham may have more grease than pork chops, increasing the chance of film interference occurring.
The color of the meat itself also has a certain role, compared to white poultry meat, the "rainbow" that appears on the dark meat of cattle, sheep and pigs is more likely to be found.
Of course, sometimes germ contamination can also cause meat to change color, but it is usually accompanied by changes in taste and meat quality, and the color will not change with different angles, so don't eat it again!
In the future, when you encounter "beauty meat" and "rainbow meat", you can eat it with confidence
Resources
Zhang Huijuan, Pan Jian. Study on the Effect of Modified Atmosphere Packaging with CO on The Effect of Ultra-High Pressure on The Sterilization and Color Protection Effect of Cooled Pork[J]. Food Research and Development, 2021, 42(12):6.
Wu Xianling, Li Xiaomin, Zhou Xueting. Application of Modified Atmosphere Packaging Technology in Food Packaging[J]. Agricultural Science and Technology and Equipment, 2021(6):2.
[3] Martinez-Hurtado J , Akram M , Yetisen A . Iridescence in Meat Caused by Surface Gratings[J]. Foods, 2013, 2(4).
[4] https://www.mentalfloss.com/article/655118/best-wireless-earbuds-under-100?utm_content=infinitescroll1