An apple turns brownish after you cut the skin off because the skin was protecting it from oxygen exposure. Without that protection, oxygen gets into its inner skin and begins deteriorating its enzymes, such as polyphenol oxidase, causing enzymatic browning.
It will turn into a rooten apple.
"Yes it is possible to cut an apple with paring knives. However, a paring knife is best used to remove the inside seeds and not cut through the skin."
it no longer has a protective layer of skin on it to delay the process
There is an oxidation process that takes place where Oxygen molecules in the air that are already extremely reactive react with enzymes in the potatoes that are activated which as a part of their reaction they turn the color of the potatoe, usually to the brownish one observed.
either no blood vesles were cut or you have exelent clotting agents
Brown streaks may very likely be caused by the larvae of the Apple Maggot.
Because oxidation kicks in after the seal (the skin/peel) is broken. To prevent this, After cutting try to use the apple the same day you cut it.
Mangoes tend to stay the same color when cut. If you cut them and do not eat them immediately or store them properly they may discolor slightly, but not on the same level as an apple.
It turns into a brownish color
Cut the Apple in pieces. Remove the skin. Put them in mixie. Add sugar and boiled, cold milk. Switch on mixie. sweet juice is ready
cause
A dull mower blade will "tear" the grass instead of "cut" it. The jagged blades of grass will dry up and cause your lawn to look brownish or even yellowish - much like when cut grass clippings turn from green to brown/yellow as they dry up.