Apple Flesh Changes When Exposed to Air

After an apple is split open and exposed to oxygen, the flesh slowly turns brown as the oxygen starts to combine with the elements and compounds in the apple. This process is called oxidation and can have different effects based on the type of apple it is and its specific contents. In the picture and the video, you can see the flesh turning brown as it continues to be exposed to the oxygen in the room. If the apple flesh was exposed to an environment with less oxygen flow then this process would have taken longer.

Driving Question

What causes an apple to change colors after it’s spit open?

Probing Questions

• As you watch the video, what do you notice happening to the apple?
• Do you think that different kinds of apples turn brown faster than others? Why?
• How can we change the apple’s environment to slow the browning process?

Classroom Activities

Students could:

• Compare different types of apples with different chemical contents to see which one browns faster. (Ex: organic vs non-organic or Granny Smith vs Golden delicious).
• Set up an investigation for children to slit open two of the same kind of apple but keep them in different environments. Check on them every 15 minutes and see which one experiences browns the fastest (Ex: one in the fridge and one by the window).

Resources

• Iowa State University Extension | Apple Varieties and Their Uses: This article lists all of the apples that are grown in Iowa. The characteristics of the apple varieties are included, which are: maturity, color, texture, flavor, storage life, uses, and bloom time.
• Iowa State University Extension | Orchards : Visit Iowa Farms: This page shows the locations of all of the different orchards in Iowa. Each orchard has a description underneath telling what they offer.
• Britannica | Why Do Sliced Apples Turn Brown?: This reading discusses why apples turn brown after being slit open, as well as recommendations for how to prevent this.
• Petroleum Museum | Apple Browning Science Experiment: This experiment tests four different theories about slowing the browning process in apples. It discusses the reason why lemon juice protects the apple from turning brown.