is eating crab season again. Have you met crab at the dinner table this year?
Under normal circumstances, the whole body of live crabs is blue and black, with the appearance of a pair of reinforced iron bones. After being steamed, it transforms greatly, the crab shells turn red, and the bright colors are even more coveted.
have eaten so many crabs, do you know why the crab shells turn red during the cooking process?
Astaxanthin : The secret of the discoloration of the crab shell
It turns out that there is a layer of dermis under the crab's shell, which is filled with many pigment cells, of which the orange-red astaxanthin is the most. The mystery of crab shell discoloration lies in it. The astaxanthin in
live crabs will combine with the different kinds of protein to give a blue-violet or blue-black color called astaxanthin. Once in a high temperature environment, such as a pot of about 100 °C, the protein will be denatured by heat, and the binding force with astaxanthin will gradually weaken. Slowly, the protein-bound astaxanthin changes back to unbound astaxanthin.
At the same time, other types of pigment cells in the dermis are slowly decomposed because they are afraid of heat. Only astaxanthin is not afraid of heat and is retained.
In addition, because astaxanthin is mostly concentrated in the claws, chest and feet, and very little in the abdomen, so "cooked crab belly white" is also a common phenomenon.
Astaxanthin not only exists in aquatic crustaceans such as shrimps and crabs, but also in the feathers of some fish and birds. The role of
astaxanthin is not just as simple as color development, it is also the strongest antioxidant in nature discovered by humans so far, and it is known as "super vitamin E" and "super antioxidant".
Three ways to choose crabs worth eating Eating male crabs, the navel of the crab is pointed, and the meat of the male crab is firm at this time.
And how to choose a fresh and plump crab is really a skill. In short, it can be summed up as three techniques of "one pinch, two amusing and three watching".
"One pinch": Pinch the crab's claws with your fingers to check the quality of the crab's flesh. Fully molted crabs generally have hard and firm claws, while immature crab claws are softer.
"two teasing": that is, teasing the eyes of crabs with hands. If it responds immediately, it is alive; if the eyes are bulging and unresponsive, it may be dead. If the crab is turned over with its belly facing the sky, it can quickly turn right and crawl, indicating that the crab is energetic; if it cannot be turned right or it is difficult to turn right, it means that its vitality is poor.
"Three looks": look at the shape of the crab. The back of the shell is dark green with luster, indicating that the meat is thick and strong; the crab navel at the tail end protrudes and reveals red, generally full of fat and fat. The most common way to eat
crabs is to steam them. After the water in the steamer is boiled, put the crabs in, steam for 5 minutes on high heat, then change to low heat and continue to steam for a while. The steaming time on low fire depends on the size of the crab. Generally, a 150 g crab needs to be steamed for about 10 minutes; for every 50 g increase in body weight, the time increases by 2 minutes.
In addition, you can also see the color of the crab shell with the naked eye. Most crabs will turn orange-red when they are fully cooked. If the color of the crab shell is blue, it needs to be cooked for a while.
The autumn wind is blowing, and the crab legs are fat. The next time you meet an old "crab" friend, you can show off that we already know the secret of its discoloration.
