Kiwifruit-marinated lamb shanks. Recipe available at www.zespri.com. Photo: SUPPLIED
This week we carry on with our home chemistry theme and mix in a bit of biology as we look at enzymes.
The background
Enzymes are biological molecules (proteins) that act as catalysts and help complex reactions occur everywhere in life.
Sometimes enzymes speed up reactions, and sometimes they slow them
down. The study of chemical reactions in living things is called biochemistry. Kiwifruit and pineapple have enzymes in them and are fun fruits to experiment with. Jelly relies on a protein to set. This protein is affected by the enzymes in the fruit.
The method
Make some jelly according to packet directions. Divide the runny jelly into several small glasses to set. Before it sets, place a small piece of kiwifruit or pineapple into half the cups. Leave the jelly for several hours to set firm. What do you notice?
The investigation
Now try a variety of fruits in your jellies -- fresh as well as canned pineapple, orange, apple and banana. What conclusions can you draw? Place some slices of kiwifruit on top of firm jelly, leave for an hour and record your findings. Some people like to put kiwifruit in a marinade for their steak. Try it and see if the steak is affected. Make sure you have a control -- some steak without kiwifruit -- to compare your results.
