In the minds of most consumers, fresh red meat is usually red, while those that are purple and brown look less fresh and even think they are spoiled. So did the meat really go bad?
Of course not. These color changes are completely normal for fresh red meat. It is the different packaging methods that change the color of the meat.
There are four main types of common packaging methods:
Packed by hand——directly in bags
Vacuum packaging—— air extraction, the packaging material is close to the meat
Modified atmosphere packaging,——filled with fresh gas in rigid plastic tray
Skin packaging,——high-end packaging, beautiful and three-dimensional, the same as vacuum packaging, the air in the package is drawn out, so that the skin-fitting film is closely attached to the product
We all understand that for fresh red meat, oxygen is an important factor affecting its appearance and freshness. The color of red meat is determined by the myoglobin molecules it contains. Myoglobin is a kind of protein, which contains iron ions, and the structure of protein + ions can make it combine with oxygen, so that the color of red meat changes.
The oxygen concentration contained in different packages is different. From the oxygen concentration, it can be determined that the molecule + ion will roughly show the following colors:
Anaerobic——myoglobin becomes purple without oxygen (deoxymyoglobin)
Micro-oxygenation,——the meat turns brown (methemoglobin)
Oxygen-rich——as in air, red
Therefore, the vacuum-packed and skin-packed meat will turn brown, and sometimes purple, because of the lack of oxygen. But when we open the package and oxygen is present again, the myoglobin in the meat will immediately react with oxygen and slowly turn back to red.
Modified atmosphere packaged red meat can maintain a bright red color for a long time due to the specific gas filled in the box. However, there is no measure for manual packaging directly in bags. After prolonged exposure to oxygen, it will start to oxidize until it spoils.
The impact of packaging on fresh red meat is the most critical and direct in the sales process. Different meats have different responses to different packaging, so as consumers, you can observe the packaging when buying, how it affects the appearance of the meat.