Enzymatic Browning and Antioxidants

Project Overview: Investigate why cut fruit turns brown, and test how antioxidants like vitamin C can slow down this enzymatic reaction. A concept widely used in food science and biotechnology to preserve food.

Materials Required:

1. 1 apple, banana, or pear

2. Lemon juice

3. Plain water

4. 3 small plates or bowls

5. A knife 

Instructions: 

1. Slice your fruit into several similar-sized pieces.

2. Leave one set of slices untouched on a plate labeled "Untreated."

3. Dip a second set in plain water for 10 seconds and place it on a plate labeled "Water."

4. Dip a third set in lemon juice for 10 seconds and place it on a plate labeled "Lemon Juice."

5. Check all three plates every 10 minutes for the next half hour.

6. The untreated and water-dipped slices should turn brown fastest; in contrast, the lemon juice slices stay fresh-looking much longer. The vitamin C (ascorbic acid) in lemon juice acts as an antioxidant, blocking the enzyme (polyphenol oxidase) responsible for browning.

Congratulations, you just discovered a natural way to fight enzymatic browning. 

Fun Fact: The enzyme responsible for browning is called polyphenol oxidase, and it's the same reason a cut avocado turns brown too.