I love bacon and eggs, but there's a downside, and it's a common household dilemma: a frypan that's encrusted with fried egg.
First I plunged it in a sinkful of hot soapy water, and took to it with a green plastic scourer. It was pretty clear that was going to work, but only after a very long time and a lot of elbow grease. Then I remembered: egg white is protein, and kiwifruit is rich in proteases (enzymes are named something-ase where "something" is the substrate they act upon. Protease breaks down protein). That's why kiwifruit is a good meat tenderiser.
So I cut a disk of kiwifruit (and ate the rest), and sat it in the frypan for a couple of hours (2h 20m, to be more precise, seeing I'm being scientific here).
Then wiped it quickly with a sponge and cold water.
So kiwifruit protease is pretty powerful at digesting protein. But enzymes are proteins too, so why don't proteases self-destruct?
Disclaimer: this research was not funded by the Kiwifruit Marketing Board.