That's due to a process called enzymatic browning, which is common in fruits and veggies (you've undoubtedly witnessed it when cutting apples or avocados, in peeled bananas, etc.).
44+ Ripe Eggplant Inside Brown. I too bought an eggplant that was about half (mottled) brown inside when i cut it open. Other signs eggplant is going bad include:
What S Wrong With My Plant Garden University Of Minnesota Extension from apps.extension.umn.edu
Unfortunately, fresh eggplant doesn't last long even with proper storage at room temperature. How to pick a perfectly ripe eggplant. If it seems lighter than you think it should, it may have lost some my favorite way to cook eggplant is to lightly fry slices (sometimes i bread them, sometimes i don't), and then put some mozzarella cheese and some.
The flesh should be all white and firm.
Only use very ripe eggplants to reduce consuming high levels of solanine. If you want to know if it is still viable as long as it isn't oozing juice or showing mold, cut into the eggplant. That's due to a process called enzymatic browning, which is common in fruits and veggies (you've undoubtedly witnessed it when cutting apples or avocados, in peeled bananas, etc.). Serve a la mode or by themselves!
