Why the shrimp head turns black: In fact, the blackening of the shrimp head has nothing to do with heavy metal pollution or freshness. In fact, it is caused by shrimp itself, which has a lot to do with the diet and growth of shrimp. It belongs to an enzymatic browning reaction in shrimp. In addition, the algae eaten by shrimp or the feed eaten by artificially raised shrimp can also lead to the black head of shrimp. This is a natural change of shrimp head, which does not mean that shrimp is polluted by heavy metals, even if shrimp is polluted by heavy metals.

It won't be so obvious on the shrimp head. It is difficult to distinguish whether there are heavy metals with naked eyes, and further detection is needed. However, it is really not recommended to eat shrimp head, which is the place where heavy metals gather in prawns. In addition, if the shrimp is refrigerated or frozen, it will indeed lead to the black head of the shrimp, but it cannot be said whether the shrimp is fresh or not.

When buying prawns, how to judge whether prawns are fresh or not? Pay special attention to the freshness of food when buying meat, and so do prawns. Everyone wants to buy fresh prawns. It is not only harmless to the body, but also tastes better.

How to judge the freshness of shrimp meat is a technical job. Pay attention to the following points when buying shrimp: whether the shrimp head is separated from the shrimp body, if so, it is not fresh; Whether the shrimp shell and the shrimp meat are not fresh; Shrimp has no elasticity, and it tastes bad without elasticity; If the shrimp shell is red, it is stale (excluding cooked shrimp), and if it smells rotten, it is stale.

In addition, you should be especially careful when eating out. Many prawns mixed in seafood stalls are stale, and prawns with particularly cheap prices are basically stale leftovers. Shrimp cooked with heavy taste may not be fresh, which is beneficial to cover up the odor!

If the shrimp you bought has no "blackheads", but it won't turn black after cooking for a while, it means that you haven't cooked it thoroughly, so you should eat it carefully.

Finally, remind everyone that when eating seafood such as shrimp and crab, you must cook it thoroughly to avoid other symptoms such as diarrhea caused by parasitic infection or bacterial infection. People who are allergic to seafood are not recommended to eat shrimp to avoid allergic symptoms.