Apple Experiment: Preventing Oxidation

Apple Oxidation by Fran W.
Why do apple slices turn brown?

Whenever an apple is cut, peeled, hit or dropped, cell walls are damaged. Enzymes called polyphenol oxidase (PPO), and iron-containing phenols are exposed to the oxygen in the air and oxidation occurs.

Fruits and vegetables such as apples, mango, potatoes, bananas, peaches and pears all turn brown (oxidize).

How can we stop oxidation or slow the process down?

- We can reduce the pH on the surface of the apple by using an acid like lemon juice.

- We can cook the apple slices to make the enzymes inactive.

- We can also stop or reduce oxidation by reducing the amount of oxygen available. We can do this by placing the apple slices in water or by putting the apple slices in a vacuum packed container.

Dehydrate the apple slices. When you dehydrate something, you remove the water and that stops foods from spoiling.

Apples by Becka V.
Try one or more ways for yourself in the following experiment...

Before you enjoy your next apple, cut two slices off and give this experiment a try:
Leave one apple slice alone and use one of the ways mentioned above to stop the other slice from turning brown. Time how long it takes for the slices to turn brown.

If you have a variety of apples in the house, cut a slice off each one and find out which apple turns brown the fastest and the slowest.


Related Apple Activities on Fran's World of Discovery:

Apple Research Project
Fran's World of Discovery has created an apple research project with links to other apples sites and videos about apples: How to make an apple puzzle, the health benefits of apples, and how apples grow.

Make a quick and easy apple cider that tastes like warm apple pie!


This experiment is an example of one of the activities that can be found in the Johnny Appleseed ebook, written and developed by Fran Wisniewski. Click on the link above to learn more or click on the link below to purchase. 
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