Hello phoebeinbrazil and thank you for your question.
Don't worry! In fact when you said "I thought exposure to oxgen caused
the meat to brown." it is the other way around ie. exposure to oxygen
turns it red. See below, and the end search strategy for more
details:
"I've noticed that packages of ground beef are bright red on the
outside, but a sort of dull grayish brown on the inside. Why is that?
And should it concern me?
It shouldn't concern you at all.
The red color of beef and other red meats is largely due to the
presence of a natural pigment called myoglobin. When the surface of
ground beef and beef cuts is exposed to air, the oxygen of the air
combines with the myoglobin to form oxymyoglobin, which is bright red
in color. This color change doesn't mean the meat isn't fresh or
edible. It's just a natural occurrence when red meats are exposed to
oxygen."
http://www.itswhatsfordinner.com/askexpert/default.asp#qa2
So in other words, your butcher was kind of correct in that if meat is
in close enough contact with other meat, then no oxygen can get to it
and it will remain brown until exposed to the air (and the oxygen)
when it will turn red.
Thank you for your question, and if you need any clarification of my
answer, do not hesitate to ask.
Very best regards
THX1138
Search strategy included:
oxymyoglobin myoglobin beef
://www.google.com/search?hl=pt&ie=UTF-8&oe=UTF-8&as_qdr=all&q=oxymyoglobin+myoglobin+beef&lr= |