Yes, the shrimp frozen in the refrigerator turns black mainly because the polyphenol oxidase in the shrimp makes tyrosine produce melanin, and there are more polyphenol oxidase in the shrimp head, so this will happen.

After being taken out of the freezer, it is put into the freezer to oxidize polyphenol oxidase, which leads to the blackening of shrimp and does not affect eating. Just remove the head and tail of the shrimp when eating.

Extended data

Fresh shrimp looks clean and feels dry. However, when the shrimp body is about to deteriorate, the granular cells secreting mucus in the lower layer of crustaceans disintegrate, and a large amount of mucus penetrates into the body surface, which feels greasy. If the shrimp shell sticks to your hands, it means that the shrimp has gone bad.

Fresh shrimps are brightly colored. Different species of shrimp have slightly different colors. Fresh shrimps, rock shrimps and grass shrimps are blue, shrimps caught in the sea are pink, and bamboo shrimps and new shrimps with knife forehead are black and white with a slight pink color. If the shrimp has black hair, it is stale shrimp, and the whole shrimp is dark and not bright, which means it has gone bad.

People's Network-Pay attention to five taboos when eating shrimp to teach you how to distinguish the freshness of shrimp.