The overall color of fresh sea lobster is relatively symmetrical. However, if it is refrigerated, we will find that some of its head turns black. In fact, this does not affect the taking and taste. This is because the carbohydrate substances contained in the brain of shrimp will change into quinones with time, and then produce pigments. If you are worried, you can also get rid of shrimp brain and take shrimp body.
The blackening of shrimp brain is not environmental pollution, but actually caused by enzyme drying. The blackening of shrimp brain reflects an enzymatic reaction produced in shrimp body, which has nothing to do with external environmental pollution. Whether shrimp is polluted by environment or heavy metal can not be distinguished according to human eyes.
A common phenomenon in animals and plants is a substance called osteoclasts. Although the structure of osteoclasts in different plants is very different, their basic functions are similar. With the effect of osteoclasts, tryptophan can gradually improve quinone compounds, and then produce dark gray substances such as eumelanin and brown melanin. This substance is the reason why the color of shrimp brain becomes darker.
The whole body of shrimp is full of osteoclasts, but the specificity of osteoclasts in the head is the strongest, and the enzymatic reaction in the abdomen and tail is low. Therefore, we always see that the brain of shrimp begins to blacken, and then the belly and tail fade.
If the shrimp is stored at room temperature, its brain will slowly darken with the passage of time, which can reflect the freshness of shrimp at a certain level. However, it is the shrimp's own biological bacteria that ultimately causes the black hair of the shrimp, which has little to do with the microbial strain. Therefore, blackening does not mean that the shrimp has already become moldy. Even under the cold storage or freezing standard, osteoclasts still have specificity, so they will still produce melanosis.
Shrimp is one of the foods that are very, very easy to mildew. Once the problem of corruption occurs, it will cause volatile acrylamide substances, soft shrimps, loss of ductility and other conditions, which are all the characteristics of the freshness of shrimps.
