Buying, Storing and Deveining Shrimp
Shrimp is a highly perishable item and should only be purchased frozen to insure freshness. Avoid buying peeled and de-veined shrimp because the shrimp can lose some of its flavor during the cleaning process. The most consistent shrimp in size, texture, and flavor are the gulf whites which come from Mexico and Ecuador. Most shrimp imported into the United States is farm-raised Ecuadorian. Shrimp are sized according to their count per lb. The best size range for value, quality, and ease of handling is probably the 26/30 range.
Shrimp should be defrosted in the refrigerator or under cold running water. Never thaw shrimp in a microwave. Any black spots on the shell of the shrimp indicates that spoilage has begun. A gritty residue on the shells indicates the product has been bleached to remove these signs of spoilage. If either condition is evident, return the shrimp to where it was purchased.
Shrimp will retain more of its flavor if it is cooked in the shell. It is a good idea to leave the shell on if poaching or grilling shrimp. De-veining is optional but be aware this gritty, stringy vein can be very unappetizing. It is preferable to remove the vein, especially if the shrimp is poached and cooked for shrimp cocktail.
Before you begin to devein your shrimp, start by keeping them in a bowl of ice water. This will keep the shrimp fresh while you are working on the others.