3 to 5 minutes can be, green beans are not suitable for a long time to cook, otherwise it will change color.

Generally speaking, prepare a clean pot, pour a small half pot of water into the pot and boil it over high heat, wait for the water to boil and then put the green beans into the pot for blanching. After about two minutes of blanching, the green beans out of the cool water to control the water and spare. However, if you buy dried green beans, you need to soak them for at least 3 hours beforehand.

When blanching, add 1% salt to the water, so that the vegetables in the saline solution, which can make the vegetables soluble nutrients diffuse into the water at a slower rate, which can reduce the loss of nutrients. What's more, it can keep the color bright green. Especially frozen green beans, but also to avoid the green beans taste astringent.

Extended information:

In the selection of green beans, you can not trust a large brightly colored, real green beans will not lose their color after immersion, after the purchase of green beans, you can use water to soak a little.

"Color" green beans in hot water in the green beans in the pigment quickly faded out of the water dyed green, placed in room temperature water over ten minutes after the color of the water will also side green, not add pigment green beans in the water is not fade.

If there is not dyed through the "green beans", a peeled, inside the buds is yellow, in addition, buy green beans, if the vendor is on the spot to open, it will be safer.