Anonymous asked "I whipped egg whites in a Kitchen Aid mixer bowl & they turned a greyish color with a grey liquid. What kind of reaction was that? And is it still safe to eat? "
I can't be sure about a Kitchen Aid bowl but whipping egg whites in an aluminium bowl will produce a grey result as small particles of aluminium are rubbed off the bowl by the beaters.
Safe? Probably but best to avoid it if you can.