Earlier this week I posted an abstract and link to a journal article
reporting on the effectiveness of preventing sliced apples (and potatoes)
from browning (due to oxidation) by using a whey or casein coating. So yes,
there's some reliable information out there, although I don't know how
commonly this process is being used. I don't usually get apples already
sliced, which seemed to be the most likely problem source, so I've never had
a reaction to apples. (And trust me, if there were dairy there, my body
would let everyone know it!) I also get fresh apples from the farmers'
market, which may help.

The bit about preventing potatoes from oxidizing was informative, too. I
always wondered why so many French fries contained dairy--now I know! That
always seemed an odd "seasoning" to me!

Weavre