[TheForge] Re: Iron in the Fire- OT now Alzheimers

[Mike Spencer]

Bruce wrote:

> If you want to use a copper kettle for cooking fudge, whipping egg
> whites, or whatever, rinse it thoroughly first with vinegar and salt.
> That mixture will remove the tarnish, JUST LIKE FOOD WOULD DO.  As
> long as the copper stays shiny or at least free of browninsh tarnish,
> it is safe to use with food.  Dry it thoroughly before putting it away
> to minimize tarnishing, but plan to clean it with vinegar and salt
> again anyway before the next use.

Gee, Bruce, that sounds pretty alarmist to me.  Even misguided.

+  The *purpose* of whipping eggs in a copper bowl is to get some
   copper ions *into* the eggs to stabilize the protein foam.  Egg
   white is slightly basic.  Having the copper bowl shiny-clean
   probably *increases* the amount of copper picked up by the eggs.

+ Ordinary copper tarnish -- like an old, brown penny -- is copper
   oxide (and possibly -sulfide), pretty insoluble and releatively
   unreactive, at least in non-acidic stuff. If it's not solube, why
   make a point of scrubbing it off and exposing the more reactive
   bare metal?

+  Subject to verifying by experiment, I'd say that washing copper
   cookware in vinegar and salt might well leave traces of copper
   acetate and possibley copper chloride on the surface.  Both of
   these are easily coluble in water so this treatment might increase
   transfer of copper to food.

+  Agreed, you shouldn't boil tomatoes, orange juice, pickle vinegar or
   any other acidic food in copper. I don't even do acidic food like
   that in *tinned* copperware.  I use stainless or, infrequently, cast
   iron. 

+ Agreed, if there is a visible accumulation of green crud -- probably
   copper carbonate, copper acetate or copper chloride -- on cookware
   it should be thoroughly scrubbed off.  Evenif it seems hard to
   scrub off, it's probably still way more soluble in water than oxide
   or straight metal.

+  I gather there are documentaed cases of people getting sick from
   drinking water from copper plumbing.  I'm guessing that these cases
   were in an area where the water was rather acidic.  But the risk if
   copper toxicity from plumbing is *reduced* by allowing oxides or
   calcareous deposits from hard water to accumulate on the insides of
   the pipes. I don't think anyone would suggest a regular vinegar
   plumbing flush to reduce the risk.


FWIW,
- Mike

-- 
Michael Spencer                  Nova Scotia, Canada       .~. 
                                                           /V\ 
mspencer at tallships.ca                                     /( )\
http://home.tallships.ca/mspencer/                        ^^-^^