Articles

    Apples with Appeal

     

    When Archie cuts up apples,
    The slices all turn brown.
    They don't look very yummy,
    Which makes his buddies frown.
    But Archie is a good cook
    Who knows a special way
    To stop the color changing
    At any time of day!

    Please note:  All chemicals and experiments can entail an element of risk, and no experiments should be performed without proper adult supervision.

    Kids, if you want to test out Archie's secret, you'll need paper towels, paper, 3 fresh apple wedges, lemon juice, and water. Spread out the paper towels. Make a large chart on the paper with columns of "water", "lemon juice", and "nothing". Place the apple wedges on the chart, one for each column. Pour some water on the first wedge, lemon juice on the second, and do nothing to the third. Wait one hour and observe your apples. What has happened? Do you know why? When it's protective skin is gone, certain substances in an apple will react with oxygen in the air and turn brown. Citric acid in the lemon juice has stopped the reaction of oxygen that turns the apple brown. This trick of using lemon juice, or orange juice, is used by Archie and many other cooks to keep apples, bananas, and other fruit looking good for fruit salads, etc.!

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    Kathleen Carrado Gregar, PhD, Argonne National Labs 
    [email protected]
    November 1997

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    Taken From: Apples, Bubbles, and Crystals: Your Science ABCs, by A. Bennett & J. Kessler, 1996, McGraw-Hill, NY.