on December 14, 2012
at 06:05 PM
I assume you are asking about polyphenol oxidase in particular -- not over heating the oil that could be extracted from the fruit right?
My understanding is that light brown is ok, dark brown/black or any change to the smell and toss it out.
I've also heard that mold will grow on the brown spots before it grows else where, so you may want to check that there's no mold.
Personally, I cut off the brown spots because they look unappetizing.