The dark line often observed in shrimp is not a vein, but rather the digestive tract, an intestinal tube that runs the length of the animal’s body. This tract contains partially digested food, sand, grit, and waste products, which is why it is commonly referred to as the shrimp’s “poop.” For many consumers, the appearance and texture of this tract are undesirable, leading to its routine removal before cooking.
Identifying the Digestive Tract
The digestive tract is found on the dorsal side of the shrimp, just beneath the surface of the flesh, running from the head down to the tail. Its appearance can vary significantly, depending on what the shrimp consumed before harvest. The line may be a prominent dark color, often black or brown, especially in shrimp that feed on muddy or sandy sea floors, resulting in a tract filled with grit.
In other cases, such as when the shrimp has been feeding in open water or if it is a smaller specimen, the digestive tract may be clear, pale, or unnoticeable. The intestinal tube is part of a digestive system that includes the foregut, midgut, and hindgut, ending in the anus near the tail. Do not confuse this dorsal tract with the nerve cord, which is a second line found on the ventral, or belly, side of the shrimp.
Deveining and Culinary Considerations
The process of “deveining” refers to the removal of this dorsal digestive tract, a step concerned with improving the shrimp’s taste and aesthetic appeal. When the tract contains sand or grit, consuming it introduces an unpleasant, gritty texture to the cooked shrimp. The contents can also impart a muddy or bitter flavor, especially in larger or jumbo shrimp, making removal advisable for these sizes.
To remove the tract, a shallow cut is typically made along the back of the shrimp using a sharp paring knife or specialized deveining tool. This incision exposes the thin line, which is then scraped out with the tip of the knife or lifted out with a toothpick. While eating the digestive tract may be off-putting, its consumption poses no major food safety concern, as cooking shrimp to an internal temperature of 145°F kills any problematic microbes.