Check out our interactiveChemistry CD-ROM.

All foods contain chemicals. Some of the most common ones are the nutrients glucose (a sugar), fat, and starch. It's not difficult to detect these nutrient chemicals in food. In this activity, you'll use simple tests to determine their presence in everyday foods.

• dropper bottles of water
• iodine (0.1 percent)
• 8 TesTape strips (2-inch [5-cm] strips)
• 8 brown-paper squares (paper sack, cut into 2-inch [5-cm] squares)
• 4 wooden tasting spoons
• 4 forceps
• 4 small plastic cups (2-ounce nut cups)
• small plate with 2 oyster crackers
• 2 miniature marshmallows
• small amount of smooth peanut butter
• small amount of unsweetened applesauce
• paper towels
• goggles
• clear tape

1. Use one of the wooden tasting spoons to crush one of the oyster crackers on the plate. With the spoon, transfer the cracker crumbs to one of the small cups. Place a marshmallow in another small cup, and use a clean tasting spoon to tear it into small pieces. Add a few drops of water to each cup to create a liquid mixture.
2. Use the two remaining tasting spoons to place half the peanut butter and half the applesauce in the two remaining cups.
3. Label four of the brown-paper squares with the names of the four foods. Use forceps to rub the second sample of each food against a brown-paper square. Place these on a paper towel.
4. Label TesTape strips with the name of each food, and then dip it into that food's cup. Place each strip on a paper towel to dry.
5. Place two drops of iodine on the food remaining in each cup.
6. Observe and the reactions in each test, recording them on the attached worksheet.
7. Compare your group's results with those of another group.
8. Now, repeat steps 1-6, and compare them with your initial results.
9. What other foods would you like to test? Develop a list of 10 additional foods with your group, and arrange to bring them in for testing. Test them using iodine, TesTape strips, and brown-paper squares. Be sure to add your results to the worksheet table.