Freshly cut surfaces of fruits and vegetables discolor when exposed to oxygen in the air. Cut three slices of a fruit (apple) or vegetable (potato). leave one unwrapped on a plate. Wrap one in plastic wrap. Dip the other in lemon juice.

1. What changes took place in each sample after 1-2 hours?

2. Define oxidation. Why did wrapping or dipping in lemon juice affect the oxidation rate?

3. Define reduction. What is a redox reaction?

4. Explain how antioxidants such as Vitamin E, citric acid, and BHT are used in the foods we eat to preserve them. What are the benefits?