I don't know that this site may help you, but it does show other things used to stop the browning of fruits and veggies. A sulfur dioxide dip is used on commercial french fries to prevent browning or oxidizing. And I have read that guacamole and avocados can also be contimanated with sulfur dioxide. Some people can have a problem with this stuff but not everyone. I think dried fruit, especially, is known for being treated with this sulfur dioxide stuff.

http://www.umaine.edu/NSFGK-12/image...r%20dioxide%22

It sounds like if you coat some foods that prevents oxygen getting to them and it stops them from turning brown. You might consider trying something like a simple sugar syrup, perhaps. Or, you might have to make your own mayo product.