Re: Is the formation of ice cream a purely physical or chemical reaction?

Amy, thanks for your question.  It is hard to give a definitive answer to 
your question because there are many areas where physical and chemical 
reactions overlap.  So, I will give my opinion on the process.  Keep in 
mind that some people may feel differently about the answer.  I consider a 
chemical reaction one where two or more substances react to form a new 
substance that is different from the original substances.   

I would say that the process of making ice cream (mixing and freezing) is 
simply a combination of physical reactions.  The process involves changing 
the viscosity of the cream and lowering its temperature—both physical 
processes.  An interaction that may be considered chemical in nature by 
some is the use of salt to depress the melting point of the ice used to 
freeze the ice cream.  This phenomenon is simply a thermodynamic process 
that I consider physical.  


Moderator's note:
Having spent a number of years making ice cream professionally, I also agree 
that the freezing process is physical, not chemical.  The liquid mix does go 
through some very minor chemical changes during pasteurizatio
n (before freezing), but the formation of the ice cream 
structure is predominantly physical.

Kieran