Shrimp two black lines do not need to be both removed, as long as the back black line can be removed. The black lines on the shrimp's abdomen are shrimp tendons, which are the shrimp's abdominal arteries and the motor nerve chains connected to them, and are edible. The reason why shrimp can bend the body and have the ability to bounce is to rely on this black line on the abdomen, i.e. shrimp tendon.

Both because of the dirt in the shrimp's digestive tract (it's the same reason we remove the gills of fish and crabs), and because the thread affects the taste, especially when steamed in white and simmered in wine.

Shrimp threads contain bitter substances that can mask the sweet flavor of fresh shrimp when heat is applied. If you're making spicy and stir-fried, it doesn't matter whether you remove the shrimp threads or not because the flavor itself is strong.

Shrimp thread:

Each shrimp's back and abdomen have a black line, the back of the black line is the shrimp's intestines, which is what we usually call shrimp thread or shrimp intestines, which are shrimp have not yet excreted things. Shrimp line in the thing is not only very dirty, and contains a number of adverse health, before cooking or eating must be removed.

To shrimp line method:

To shrimp line method is very simple, you can first choose some fresh large basal shrimp, so that the shrimp line will be more quickly, but also to prepare a tweezers, the first hand to the shrimp pinched, the shrimp's tail countdown to the second section of the tweezers inserted to be able to directly to the shrimp line pick off.