Hello Whenpigsfly,

Seviche, the cooking technique of using Lime juice to cook fish and sea food is one way to <cook> without heat.  
It is true that a piece of salmon left to sit in lime juice will become opaque, milky and change to a paler colour similar to how it would appear if it was steamed for example.

Heat and acid affect proteins (found in meat, fish, etc).  The term is denaturing which essentially means to render non-functional in a irreversible fashion.   Eggs is a good example on how denatured proteins manifests themselves:  an egg cracked in a hot skillet will change to an opaque. milky white from a watery clear liquid in the case of the egg white.  Eggs are less affected by acids which helps when making mayonnaise.  

Acids denature milk proteins which manifests as curdling yet cooking does not affect milk that much.

In the case of muscles (meat) both heat and acids denature the proteins in a similar fashion.

I hope this helps!
Luc H.

Hello,
One way for scientist to describe proteins is by their shape, which in turn corresponds to their molecular function.  A common model is the "lock and key", so if a protein changes shape from its normal natural state it does not work.  Hence a lot of research is performed  understanding the ins and outs of protein structure.

Ok so how does this have to do with your post?
All proteins have a "natural" shape that allows it to fulfill its function.  This shape/structure of proteins is sensitive to changes in pH and in temperature.  Change either pH or temp and the protein may unravel or fold up in different ways, suddenly the protein is no longer in its natural state but in a "denatured"  state.  
The acidity in lime and lemon juices lowers the pH enough that the proteins in seafood are changed from their natural state to a "cooked" or "denatured" state.  Basically you are using a chemical process to change the protein structure.  I hope this helps!

ou don't "cook" without using heat.  However, as you are clearly implying, you can prepare some foods by use of common food acids. Ceviche (Seveche or Seviche by some), refers to a style of food preparation using citric acid found in limes and lemons and which is sometimes used with vinegar to prepare seafood dishes. It doesn't really "cook" the food, but the chemical reaction that occurs does make the food appear to be cooked as if by heat.

You marinate meat in vinegar (and other acids like the limes and lemons) to either flavor the food, or to help break down the chemical structure of the food in order to help different texture in the meat or, in some cases, help tenderize it.

Would this heatless cooking method have the same effect on a food's deterioration process as cooking with heat?  Can fish cooked with acids be stored in the refrogerator as long as fish cooked using heat?

Not heard of the technique before but whilst looking I came up with this which may be of interest.
http://ourman.typepad.com/omig/2007/06/how_to_cook_a_f.html
I think you need to be careful how long you leave the lime juice on for as its an acid and will eat away the fish.

You don't "cook" without using heat.  However, as you are clearly implying, you can prepare some foods by use of common food acids. Ceviche (Seveche or Seviche by some), refers to a style of food preparation using citric acid found in limes and lemons and which is sometimes used with vinegar to prepare seafood dishes. It doesn't really "cook" the food, but the chemical reaction that occurs does make the food appear to be cooked as if by heat.