1, cold water in the pot can better remove astringent flavor. Because the astringent substance of asparagus does not only exist on the surface, asparagus internal astringency is also obvious, so if it is hot water in the pot to cook, asparagus into the pot after the surface will immediately set hard, resulting in internal astringency can not blanch blanching, so the taste will still be very astringent;

2, cold water in the pot can be more thorough removal of oxalic acid. Because oxalic acid itself is accompanied by the growth of asparagus together with the distribution of asparagus meat, so the asparagus oxalic acid should be inside and outside the distribution of uniform, so if the hot water pot asparagus can only remove the surface of the oxalic acid, can not be completely removed from the internal oxalic acid, ate the risk of eating, and the cold water pot can be from the inside out of the slow heat penetration, so the oxalic acid can be removed more thoroughly;

3, The hot water under the pot will destroy the taste and nutrition. Because hot water in the pot is heated too quickly, asparagus will be cooked immediately after the pot to the stereotypes, resulting in the back not only astringent and oxalic acid is difficult to remove, in the taste will be hard and difficult to fry, cooking is also difficult to fry faster, affecting the finished product texture and flavor, and instant contact with high temperature asparagus nutrients are also easy to denature, resulting in the final nutritional reduction.