Can I eat brown apples?

pu1. Vegetable tissues such as apples, bananas, and tea potatoes often contain high levels of phenolic compounds such as catechin, catechol, gallic acid, and tyrosine, and usually these foods themselves contain "Polyphenol Oxydase," an enzyme that oxidizes the phenolic compound.
If you peel or scratch fresh fruit, there are no reports that this enzyme is secreted and reacts with oxygen to oxidize polyphenols to produce brown substances, but it's better to eat it before browning because it's not good enough.
It says so

2017-12-19

OK

pu2. You can just eat it because it's simply oxidized polyphenol and browned. It's just that it doesn't taste good

2017-12-19

OK