Chemistry in Foods

Viva Henson                    Andrew Jackson
                               1340 W. Harrison
                               Chicago, IL 60609
                               312-534-7000

Objectives:

To develop an understanding of the function of indicators.
To develop an understanding of some simple chemistry concepts.
To identify acids and bases in foods.
To develop skills recording information and keeping charts.

Materials:

For each group of 4 or 5 students:

   cabbage indicator paper
   blackberry indicator paper
   onion indicator paper
   aluminum foil or small aluminum, styrofoam or plastic trays
   various juices and foods--such as: corn, apple juice, pickle juice,
   orange juice, rhubarb, potato water, rice water and baking soda
   plastic cup of water

Strategy:

1.  This activity will be done after the teacher has discussed indicators, acids 
    and bases and has tested several household products by using litmus paper. 
2.  This activity will be done with the entire class in groups of four or five. 
3.  Each group should have at their stations a few strips of each of the 
    indicators, samples of all of the food items, a plastic cup of water and 
    aluminum foil, styrofoam, aluminum or a plastic tray on which they will lay 
    their indicators after they have been dipped into each of the juices and 
    foods. 
4.  After each food has been tested, the students are to record their findings.

      Blackberry Indicators -- turn blue when dipped in a base and red when
                               dipped in an acid
      Onion Indicators      -- turn green when dipped in a base and colorless
                               when dipped in an acid
      Red Cabbage Indicators-- turn green when dipped in a base and red when
                               dipped in an acid

Summary:

     Students will understand that there are two classes of chemicals which can
be indicated by using colored indicator paper.  Students will also discover that 
in order to test for acids and bases the food must be wet or in liquid form. 
Through discovery, students will pour water into the baking soda to get a 
reading using the indicators.  Students will understand that there are chemical 
compounds in foods and there seems to be a higher number of foods with acids 
than bases.