Why does egg burst in a microwave and steamer but not in boiling water?

Answer 1

Well to understand this first you should know how a microwave oven works. A microwave oven works on the microwave frequency which is 2.45Ghz. Well this frequency is capable of heating water particles more because of the greater absorption factor.

The water particles in the food is heated which in turn heats the food in microwave oven.

Now lets take the case of 'egg'. The egg shell is made of calcium. The egg white have high quantity of water and the yolk contains fat.

When heated in a microwave, the temperature reaches a higher range exponentially and the water in albumin the egg white is vaporised. There is no escape of this expanded water. This leads to the explosion of egg.

Now in case of boiling water. There is no sudden rise in temperature, So there is even heating of the shell and the inside of egg. In this the calcium shell also expands a little because its contact with water. And the albumin doesn't reach high temperature like that in microwave.

Answer 2

It's a matter of varying rates of energy transfer, and differences between relative elasticity, expansion & contraction rates of the various composites &semi-rigid structures,of which the sum total represents a tomato in it's natural hydrated state at ambient temperature at 14.7 psi.
Bombardment of said tomato by micro-wave radiation more readily agitates the molecules of the semi-liquid composite that encapsulates the seed mass, creating pressure and steam at a rate disproportionate to the more fibrousness outer mantle and skin. In this instance,the resulting effect of pressure overload is a sudden and catastrophic breach of structural integrity. The pressure develops in the semi liquid core as the energies vibrate the molecules resulting in heat that's transmutes the liquid into an expansive gas and radiates outward. This effect is often mistaken, over-simplified and mis- characterized as a 'bursted tomato. It is not quite so vulgar as that, as you now know.

The steamer "achieve's" a similar yet different effect. Due to the different type of energy and radiation being applied in the steamer, the manner in which a breach occurs is markedly different from the microwave induced rupture.
The variation is not unlike the difference between a bubble and anti-bubble.That much will become clear when we observe the boiling water.But I digress.....forgive me.... I was and shall now continue with how the steamer effects a total rupture in a way different than results from bombardment by microwave radiation.
In this case the external surface area of the tomato directly interfaces with the higher temperature environment of the steamer gases ,thus facilitating a too rapid transfer of energy , causing variation in surface tension and contraction between the fine outer skin and immediate underlying flesh, resulting in a breach of structural integrity nearer to the surface in this instance.Compare and contrast with the radiation induced, centrally emanated, expansionary rupture from the inner-core outwards.
Now a caveat before I proceed, I have personally witnessed and in fact have experienced a ruptured tomato during ill fated attempts to blanch by brief immersion in h20 @ 100c, followed by induced rapid cooling via immersion in ice bath to enable efficient removal of the skin for research purposes only, I candidly assure you of such.
Being an out-spoken advocate for life in all it's forms I do not readily countenance the subjecting of vegetables to such horrors for anything other than the necessity to immediately alleviate famine.That much being said, I quickly find it tiresome to dwell on the ethics and morality of vegetable consumption, be it ill-advised and politically correct or not. Science can be pure, can the same be said for subjectivity.....I think not.....consequently I rest my case and withdraw from the controversy.
I can now return to the elegant simplicity and pure innocence of science.
An anti-bubble is a sphere of liquid contained by ambient pressure of the gas surrounding it, which is the opposite of gas contained within a film of liquid ie: a regular bubble,which even in the mind of children young and old has mystical properties that please & inspire.
Now understand the more gentle and subtle forces at play when immersed in h20 @ 100 c .It is a balance and combination of these forces that generally inhibited breach or rupture of a tomato upon immersion. For sake of brevity, I will not discuss the merit of any particular regional variety regarding ultimate end use or variation and resistance to rupture based upon differing genetic characteristics of cellular structure, flesh density, skin resiliency and or general versus irregular shape.
That being said...I can now continue for the benefit of those who are unable to do anything else but finish reading what they started. I mention only in passing that I have always struggled with deciding whether that particular attribute is a virtue or a vice.
By now our tomato anticipates it's ultimate fate, as through means not quite understood yet observed, plants send out signals through chemical means, that indicate stress or what we perceive as threat or danger. Realization of such shall not result in mercy for the tomato, no recourse or quarter shall be offered nor granted or given. Agreed it is, that a certain and cruel fate awaits this tomato, soon to be sacrificed upon the altar of science ....such is the cycle of life.
Finally.......... When submerged, the tomato finds itself absorbing and transferring the heat at a different rate then when enveloped in the heated gaseous environment of the steamer. The difference in pressure while suspended in liquid has a beneficial and synergistic effect and exerts a stable and moderate pressure evenly, subjecting the tomato only to the random and chaotic effects of impingement, and the tempest in a teapot micro-verse that briefly exists when a heat or ultrasonically induced micro-bubble implodes in proximity to a metallic substrate. The tomato, being generally recognized as a non-metallic object(other than the molecular Fe of the tomato itself) does not suffer the potential effects of rupture by means of sustained cavitation .
It is a combination of factors that allows for a more gradual increase of the outer skin and inner flesh to react in a more uniform and consequently less disruptive and debilitating manner, structurally speaking.
This gradual acclimatization, proportionate to the torsional strain never quite reaches the point of no return thus retarding rupture of the skin but not external deformation from internal structural changes. The integrity of the envelope remains intact as the questioner so rightly observes.
I hope this brief over-view can provide a simplistic generalization that skims the surface of the basic under-lying dynamics at play when subjecting tomato's to various states of radiant energy in an effort to understand the observable physical reactions and subsequent and resulting change in states of vegetative matter.
Now if I admit to believing in and pay lip service to global warming will Obama give me a grant ?