1. Brown-Out: A Student-Designed Scientific Method Experiment
Apple Inquiry Lab
Brown-Out: A Student-Designed Scientific Method Experiment

2. Observations
Sketch and describe what you see as you examine the different apple slices.
With your lab groups, answer the following questions:
In what order were the slices most likely cut?
Which slices are similar in color?
How uniform is the color?
How deep is the color in the apple?

3. Questions to Discuss:
What do you think is causing this browning phenomenon?
How can this browning be prevented? (Generate a list of ideas with your lab group)

4. Experimental Design Use control and experimental groups
Independent Variable – what is manipulated/changed in the experiment
Dependent Variable – what is measured
Hypothesis: If [independent variable], then [dependent variable] because [scientific reasoning].
Control: what you compare experimental groups to
Constants: what you keep the same between all test groups

5. Design Your Experiment
Choose 1 factor to test in an experiment.
Design an experiment.
Develop a hypothesis. (If… , then…. because…)
Determine what materials you will need for your experiment. Make a list.
Write a list of your procedures.

6. Experimental Results
Make appropriate data tables and record results from your experiment.
Conclusion:
Explain your results.
Did your results support your hypothesis? Why or why not?
Were there any errors? How could they be prevented?
Where would you go from here? What would you test next?

7. Apple Browning Enzyme: Polyphenol Oxidase (PPO)
On the presence of oxygen, PPO converts plant phenolic compounds to brown pigments called melanins
What treatments decreased browning in your apple slices?

8. Methods for preventing fruit browning:
Sulfites – prevent melanin formation
Ascorbic acid (vitamin C) – antioxidant that reacts with PPO instead of oxygen
Acids (citric acid or acetic acid) – lowers pH to slow the action of PPO
Water bath – restrict contact with oxygen
Boiling – inactivate (denature) PPO enzymes