原文: 鸡蛋怎么煮才最营养又好吃

　　1、泡水 

　　在煮鸡蛋之前，最好先把鸡蛋放入冷水中浸泡一会儿，再放入冷水锅中煮沸，这样蛋壳就不易破裂了。当然，这只是保持鸡蛋外形完整的方法之一。

　　2、火力 

　　煮鸡蛋时若用大火，容易引起蛋壳内空气急剧膨胀而导致蛋壳爆裂；若使用小火，又延长了煮鸡蛋的时间，而且不容易掌握好蛋的老嫩程度。实践证明，煮鸡蛋以中火最为适宜。

　　3、时间
 
　　在确定了火力大小之后，只要准确地掌握好了煮蛋时间，就能够随心所欲地控制蛋的老嫩程度。例如，煮软蛋，水开后煮3分钟即可。此时蛋清凝固，蛋黄尚呈流体状；煮溏心蛋，水开后煮5分钟即可。此时蛋清凝固，蛋黄呈稠液状，软嫩滑润；煮硬蛋，水开后煮7分钟即可。此时蛋清凝固，蛋黄干爽。需要注意的是，煮硬蛋时切不可随意延长时间。因为鸡蛋在沸水中煮的时间过长、超过10分钟时，鸡蛋内部会发生一系列化学变化，从而降低鸡蛋的营养价值。

　　4、搅动 

　　为了使蛋黄凝固在蛋清的正中间，应在鸡蛋下锅后用手勺不停地顺一个方向搅动，使锅中的水呈漩涡状转动，直至煮熟。至于这是什么原理，想必与物理学上的离心力、向心力有关吧。

煮鸡蛋5分钟最好

      煮鸡蛋看似简单，却不好把握火候，时间过短会使蛋黄不熟，时间过长会使鸡蛋变老不好吃。对此，北京大学第三医院运动医学研究所常翠青博士介绍，其实煮鸡蛋的最佳时机很好把握。

      凉水下锅，水开后算好5分钟，煮出来的鸡蛋既被杀死了有害致病菌，又能比较完整地保存营养素。

      如果鸡蛋在沸水中煮超过10分钟，内部会发生一系列的化学变化。蛋白质结构变得更紧密，不容易与胃液中蛋白质消化酶接触，所以较难消化。蛋品中蛋白质含有较多的蛋氨酸，经过长时间加热后，它会分解出硫化物，它与蛋黄中的铁发生反应，形成人体不易吸收的硫化铁，营养损失较多。

      煮不熟的鸡蛋危害更大。生鸡蛋不但存在沙门氏菌污染问题，还有抗酶蛋白和抗生物素蛋白两种有害物。前者会影响蛋白质的消化吸收；后者能与食物中的生物素结合，导致人体生物素缺乏，产生精神倦怠、肌肉酸痛等症状。而鸡蛋一经煮熟，上述两种物质才会被破坏。

　　此外，煮蛋时还可掌握以下技巧，以防止营养素的流失：水必须没过蛋，否则浸不到水的地方蛋白质不易凝固，影响消化；煮前把蛋放人冷水浸泡一会儿，以降低蛋内气压；然后用中等火候，冷水煮沸，即可防止蛋壳破裂，避免营养素流失。

译文: How to poach eggs to the most nutritious and delicious

Factor one 、Soak in water

　　Before poaching eggs,you'd better lay the eggs under the cold water for a while and place them in the pan of cold water for cooking,after that doing,the egg isn't liable to be broken down.Of course,it's only one of the methods for holding the complete shape of egg.  

Factor two、Heat control 

　　If cook the egg by using the hard fire,it easily induce the air expand sharply within the egg causing the shells into crash;or using the opposite will prolong the duration of cooking even hard to control the degree of eggs.According to the experiments,it's most appropriate to use the moderate fire for cooking the eggs.

Factor three、Duration
 
　　After ensuring the extent of fire,you can control the degree of maturity of eggs as you wish only if acurrately you master the time of poaching eggs well.For instances,it's fit for poacing the soft-shelled eggs for three minutes after the water is boiling  when the egg white solidify ,the yolk is in the form of fluxion;cooking soft eggs for five minutes after the water is boiling when the egg white solidify,the yolk is in the form of thick liquid,soft and smooth;cooking hard eggs for seven minutes after the water is boiling when the egg white solidify,the yolk is dry.The note for poaching hard eggs is that not prolong the duration arbitrarily for  when cooking the eggs too long in the boiling water up to ten minutes thereby happen a serie of chemical reaction in the internal eggs and low the nutritious value of egg.

Step four、Stir

      For enable the yolk curded in the very center of egg white ,it ought to stir towards one direction continually after placing the eggs into the pan leading the water in the pan spinning in whirllike formation till mature.Refer to the theory which must be related to the centrifugal force and centripetal force in physics.

      It's best to poach eggs for five minutes

      Poach eggs seems to be simple but it's hard to control the fire that the yolk is raw if duration is too short or reversely the egg changes into hard and is unsavory.At that point,introduced    by Doctor.CuiQing Chang the sport science institute of the third hospital in Beijing University that in fact the best opportunity of poaching eggs is easy to hold. 

      Pour the cold water into the pan and cook for caculated five minutes after the water is boiling then the product not only kill the harmful bacteria,but also comparatively keep the nutriment completely.

       If poaching eggs in the boiling water over ten minutes,it induces a serie of chemical reactions within the eggs that the structure of protein turns more close which is idle to protein digestive enzymes in gastric juice,so it's hard to be digested.Protein in the terms of eggs contains quite much amino acid  which after being heated for long time will decompose sulfuret which reacts with the iron in the yolk then form the iron sulfides that is hard to be absorbed by body,thus cause mass loss of nutriments.  

      The uncooked eggs are more harmful.The raw eggs not only cause the problem of pollution of salmonella  but also have two kinds of noxious substance as anti-enzyme protein and antibiotic protein  inside.The former will influence the intake of protein;the later can combine with the biotin  in food causing the defect of human biotin and inducing the phenomenon of tired mind and painful muscle .While neither would the two above mentioned material be destoryed until once the eggs are mature . 

      Otherwise,you can learn the skills below to prevent the nurtrion from escaping when cooking eggs:the water must overcome the eggs or the protein in the uncovered site is hard to solidify and affect the digesting;before poaching place the eggs in the water for a while for lowing the internal air pressure of eggs;thereby cook the cold water  up to boiling with moderate fire that shall prevent the shells from breaking down and avoid the flow of nutriment.