What is the reason why cooked beef is rainbow-colored after slicing?

I don't know if you noticed when you were eating beef. Sometimes the beef slices we pick up with chopsticks are rainbow-colored. It is doubtful whether the beef has gone bad or something like fluorescent agent has been added. But this is actually a normal phenomenon. If you have paid attention to it, you may find that this rainbow color phenomenon mostly occurs in lean parts such as tendons. This is because the rainbow color has a major premise, that is, the fat content in meat is low, the meat quality is dense and uniform, and it is easy to form a large area of light-receiving surface. Then, under the influence of light and the action of trace elements such as iron and zinc rich in beef, it became a different rainbow color.

Rainbow beef

I checked the information and found that this phenomenon is called diffraction grating.

Most vertebrate muscles have a typical sarcomere structure, but our muscles are composed of countless such fibers, and the contraction of many muscle fibers is reflected in the macro-contraction of muscles. When we enlarge the muscle fiber further, we will find that it presents a typical structure, which is called sarcomere.

This sarcomere consists of thick and thin myofilaments. When the level of calcium ion in muscle cells changes, driven by the energy provided by ATP, the structure of actin in muscle changes, which pulls the myofilament to slide and the muscle moves.

Currency tendon

Then when we cut the muscle fiber with a knife, there will be many cut muscle segments on the section. These muscle segments form a ladder structure. When visible light shines on this plane, the emergent angles of different wavelengths of visible light on this plane will change, so different colors of visible light will be separated, and then we will see the "rainbow" in the meat.

If the meat is not fresh, the sarcomere structure may dissolve under the action of spoilage bacteria and cell autolytic enzymes, so it is difficult to see the rainbow luster after cutting.

So this rainbow color is also the representative of fresh and healthy beef! However, this phenomenon is relatively rare, and the probability of occurrence is relatively small. Most beef is normal color. When buying beef, the most important thing is to choose a good brand that can be trusted. Eating good meat will make it fresh. The original cut steak is delicious without meat. The chance of encountering a rainbow is higher!