Friday, 27 July 2012

Kiwi(fruit) power

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.


  1. I assume the fact that the protease does not self-destruct is due to the inherent nature of enzymes, i.e. containing a binding site that is highly specific for an amino acid/s where the reaction takes place. (Lock and Key analogy).

    This level of control is further enhanced by various complex co-factor/inhibitor pathways.

    Cool article, I wonder how viable it is to extract the protease from the kiwifruit and store it as a specialist 'dish washing liquid'. If you're lazy you could purchase the commercially available meat tenderizer. :-)