Krampf Experiment of the
Week -
#109 The Power of Lemons
http://www.krampf.com
This week's shows went very well, especially Saturday's programs at
the Museum of Natural History in Gainesville, FL. We had a very good
turnout and I got to watch Dr. Henri Van Rinsfelt do his Physics is
Fun show, which was wonderful. I also met Art Yeaman, who does a
wonderful job of portraying Benjamin Franklin. All in all, it was a
marvelous day.
This week's experiment is a fun one and a yummy one too (I was hungry
while I was choosing it). We are going to experiment with the impact
that vitamin C has on the browning of fruit.
You will need:
* some lemon juice or a fresh lemon
* an apple
* a banana
* any other fruit you
want to try
* two bowls
Peel the banana and cut it into slices. Put half the slices in
each
bowl. Do the same with the apple. Now, sprinkle lemon juice over the
fruit in one dish. Gently stir the fruit so that it all gets coated
with the lemon juice. Leave the other bowl just as it is. Now wait.
While you are waiting, you can nibble on some of the fruit from each
bowl, as long as you leave enough to see the results. Examine the
fruit every 10 minutes for an hour. What do you notice?
You should see that the fruit without the lemon juice quickly begins
to turn brown fairly quickly. The fruit with the lemon juice will not
brown as much and will take longer to brown.
Why does this happen? The fruit contain chemicals called enzymes.
Some of these enzymes combine with oxygen in the air and turn brown.
When the fruit is cut, oxygen can reach the inside of the fruit,
where the enzymes are and it quickly changes to a brown color. The
lemon juice helps slow the browning for two reasons. First, it coats
the fruit, helping to keep the oxygen in the air away from the fruit.
More importantly, it contains vitamin C, which is an antioxidant. You
may hear the word antioxidant in television commercials. It means
that vitamin C prevents the enzymes from combining with the oxygen.
The vitamin C is used up as it does this and eventually the fruit
will turn brown anyway.
You may want to take this experiment a step farther and try coating
some of the fruit with water, some with oil, etc., to compare the
advantage of coating the fruit with vitamin C with fruit that is
coated with other liquids. You can also test other plant materials,
such as lettuce and avocado. These also turn brown when cut in the
presence of oxygen.
When you finish, mix your cut up apples, with the cut up bananas. Add
a little sour cream, some orange slices and maybe some coconut and
marshmallows and you will have a very tasty fruit salad. The lemon
juice will add nicely to the flavor, along with keeping the brown
color away.