SC - Organic Chem and YOU! (Was Re: Warm Apple Reaction)

[Rodney K Zeigler]

from "Decker, Terry D." <TerryD at Health.State.OK.US>:

> Ask your biology professor, if the act of cooking would accelerate the
> hydrolysis of pectin into pectic acid and methanol and if cooling the
> cooked material would partially reverse the process.  The catalytic
> enzyme in the process is pectinerase.  If what I suspect is correct, the
> allergic reaction is to an increased amount of pectic acid or methanol
> in the heated product which recombines as the product cools.

I'm not as biology prof, but I am a bio major with a semester of O-chem 
under my belt, so I'll give it a whirl.
I'm not familiar with the breakdown of pectin into methanol, but I will 
assure these things:

1. Cooking would speed up the reaction in two ways: a.) by providing 
heat(and therefore energy) to the reaction and b.) by freeing water as 
steam to shift the equilibrium toward the production of methanol. 

2. By this same mechanism, the pectic acid and methanol wouldn't be able to 
recombine in the cooled state, because the water would be present and 
reaction energy would not be. This is the reverse of the process by which 
every O-chem student makes banana oil, in which concentrated sulfuric acid 
is used to remove the water from the reaction and drive equilibrium toward 
combination of amyl alcohol and acetic acid.

Of course, I wasn't even aware that pectin was an ester until a moment ago, 
so I could be wrong. 

Kent "1,1,1,2 tetra-fluoroethylene" Zeigler 




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