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Sheldon

wrote:
> Does anyone elses kitchenaid mixer paddle leave gray stains on the
> food? It's particularly obvious on cheesecake, with gray swirly
> markings on the finished product. Have seen when mixing cornbread also.
>
> Any ideas?

Most dough hooks (like many meat grinder augers) are of *cast* metal
(as opposed to machined - machining these items would make them
prohibitively costly, only NASA could afford them) therefore are
*porous* to some degree. Because of the porosity of these articles
some quantity of the oils naturally present in foods will be absorbed,
leaving these articles "charged", just like "Oilites" (porous bronze
bearings). If occasionally you boil your dough hook for a few minutes
(in *plain* water) much of the absorbed oils will be extracted. Often
the metal used for dough hooks and augars is aluminum... the dark
smearing you see is NOT aluminum (not unless the aluminum is rubbing
the bowl), it is food fat... can't hurt you but is not very attractive.
Sometimes with stand mixers a small quantity of lubrication will run
down from the gear head, it will run onto the dough hook and become
absorbed too, but that also won't hurt you, it's just ugly. Simmer
your cast aluminum dough hooks, beaters, and grinder augers every so
often... you'll see the dark sludge rise to the surface.... washing
with dish liquid won't help and dish washing machines will destroy the
finish of aluminum. And do not use any abrasives on aluminum...
aluminum is soft and will become "charged" with the abrasive particles.
Some of the newer cast aluminum articles are coated with some sort of
plastic, I don't know that ingesting bits of that plastic is any
better... and soon as some plastic wears away the bare cast aluminum
will become exposed, so then it will absorb oils too.... so don't go
run out to replace your old with new.

Commercial quality mixers and grinders are fitted with cast stainless
steel attachments... even though slightly porous as well those can
safely go into the dishwasher.

Sheldon