Bad shrimp may cause an outbreak of food poisoning among your family members or dinner guests, or it may simply result in an inedible seafood dish. Look for signs of bad shrimp before purchase, if possible, to ensure you serve only healthy, delicious seafood. If you can't detect signs of spoilage in prepackaged shrimp and discover the shrimp are bad when you unwrap them, immediately return them to the seafood dealer.
Your sense of smell is your best tool in detecting signs of bad shrimp early. Fresh, unspoilt shrimp should give off a slightly salty odour, if they have any odour at all. Shrimp with an overwhelming fishy odour may be past their prime, and the smell of ammonia or bleach may indicate the growth of bacteria that could lead to food poisoning.
The shells on good raw shrimp should be clean, translucent, firm and glossy. Black spots on the shell may be a natural and harmless enzymatic reaction, according to the American Culinary Federation, or they may indicate poor harvesting or processing procedures. Check for other signs of spoilage before purchasing shrimp with black spots on the shell. Do not purchase shrimp with yellow or gritty shells; these signs may indicate the shrimp were chemically treated to mask spoilage.
Meat Color and Consistency
Good, raw shrimp bodies should be firm and translucent, although the overall colour may vary from white to light green, depending on the variety. Raw shrimp meat with opaque spots may be spoiled. The shrimp should still be attached to the shell; if the shrimp's body has detached from the shell or has fallen apart within the shell, it's likely bad. Cooked shrimp meat should have a firm, white interior with a hint of pink on the exterior; don't purchase or eat mushy cooked shrimp.
Raw or cooked shrimp with the heads still on are likely to have a better texture and flavour than headless shrimp, and you'll see more signs to determine if the shrimp are bad. The eyes should be glossy and moist; if they are missing or shrunken, the shrimp may not be fresh. Raw shrimp heads should be firmly attached to the bodies, and you should have to use a firm pinch to remove the heads from cooked shrimp. Loose heads may be signs of bad shrimp.