Activity:

1. Divide the class into cooperative groups of 3-4 students. Explain to the students that their challenge is to find a way to prevent a variety of fruits and vegetables from turning brown.
2. Outline the safety requirements students should follow when using a knife.
3. Introduce the potential treatment options for the fruits and vegetables:
   • Lemon juice
   • Pineapple juice
   • Sodium bicarbonate solution (1 teaspoon of baking soda dissolved per 100 mL of water)
   • Ascorbic acid solution (1 crushed vitamin C pill dissolved per cup of water)
   • Citric acid solution (1 gram of citric acid dissolved per 1000 mL of water)
   • Plastic wrap
4. Have the students record their hypotheses on The Chemistry of Fruits and Vegetables activity sheet.
5. Instruct groups to select two types of vegetables and two types of fruit for their experiment. Students will need to slice three equal portions (one control and two different treatments) of each fruit and vegetable.
6. Without delay, treat the three slices of each type of fresh produce as follows:
   • First slice: leave exposed to the air (the control)
   • Second slice: apply treatment of choice to all exposed surfaces
   • Third slice: apply different treatment of choice to all exposed surfaces
7. Have the students record their observations on The Chemistry of Fruits and Vegetables activity sheet. Observations should be made and recorded immediately after cutting and at regular 10-minute intervals for 30 minutes.
8. After the students make their final observations, hold a class discussion about produce discoloration and the effect different treatments have on fresh produce. Take time to discuss the real-life application of their experiment, as well as the types of discoloration that affect the healthfulness of food, such as mold and bruising.
9. Have the student groups discuss the results as well as draw and write conclusions. Students should be able to make conclusions about the following and then complete their activity sheets:
   • How does the naturally occuring ascorbic acid content of different types of produce affect the rate in which they brown?
   • What treatment is most effective in preventing discoloration?
   • As consumers, how will the results of this experiment affect how they store food?
   • As scientists, what additional information would they want to know before marketing their solution to consumers?

Variations

• Have the students write a formal lab report, which includes a purpose, hypothesis, materials list, procedure, results, and conclusion.
• Before the activity, have the students predict what the results of the experiment will be (hypothesis). After the experiment, have the students compare their data with their predictions.