The black line in shrimp, often called a “vein,” is actually its digestive tract or intestine. It may contain sand, sediment, or undigested food, but eating it isn’t dangerous if the shrimp is properly cooked, as heat kills any harmful bacteria. The concern is more about texture and flavor; it can be gritty or slightly bitter.
For larger shrimp, it’s recommended to remove the vein as it’s more visible and likely to contain debris. In smaller shrimp, it’s often left intact since the impact is minimal. If you’re preparing delicate dishes like ceviche or aiming for a clean presentation, it’s best to remove it.
To remove the vein, make a small cut along the shrimp’s back, lift the vein with a knife tip, and rinse the shrimp under cold water.
While it’s not harmful, whether to remove the vein depends on personal preference for taste and presentation.