Design an experiment to test for the presence of a protein digesting enzyme in papaya?

Question

Design an experiment to test for the presence of a protein digesting enzyme in papaya?

Answer 1

Unripe papaya flesh, especially skin, contains the enzyme papain, which dissolves long protein chains-- hence making meat tender.

I'm not sure as to the concentration of papain per cultivar or by weight, but as a good scientist it's important to have comparisons.

I would probably buy tough meat, like brisket or chuck cuts. Place a chunk or two of uncooked meat in the fridge (covered of course, so it doesn't dry out) as a "control".

There are two main types of papaya sold in commercial groceries: maradol, which are the big ones, and "strawberry" papayas, which are considerably smaller. Buying a variety of papayas lets you see if some papaya have more papain than others.

In separate containers, pour pureed GREEN papaya over raw meat, cover, and refrigerate.

I don't know what a sufficient wait would be, but after a few days it would probably be evident if the papaya tenderized the meat by comparison to your "control" sample.

Edit: I agree with the idea of using gelatin, except you must take care. Protein based gelatin (made from animal skins and hooves) will not remain set at room temperature and must be refrigerated. Gelatin that WILL stay gelled at room temperature is most likely agar, which is a starch based gel and does not contain the necessary protiens. Either way you're going to need a fridge.

Answer 2

Using tough meat is the tough way to do it. It is much easier to use gelatin as your medium. Fill a bunch of petri dishes with prepared Jello or another brand. On each one, place a piece of the papaya: skin, flesh, seed. On another series of dishes, place the same parts of the papays after denaturing their proteins, as by cooking. Compare the results.

Answer 3

An Experiment for the Gourmet Scientist.

The papaya's seed is loaded with pepsin which digests protein. Take the seeds out of the  papaya and smash them so they are open. Take a piece of tough meat and place it in a plastic bag with the smashed seeds and refrigerate 2 4-48 hours. Remove the seeds from the meat. Discard  the seeds. Cook the meat (it will be very tender) and serve with sliced papaya. This is how my mother learned to prepare old  tough roosters when she lived  in the Philippines 60+ years ago.

There are lots of pepsin / antacid tests you can do, too.

EDIT: The kitchen is one of the best places at home for science experiments; however, I like Oikos answer for its clean design as a classroom experiment. Add a second set of seeds to his design - one petri dish with  whole seeds and a second with cracked seeds to see if that changes the  seed  results.