Why Do Apples Turn Brown?

Why do apples turn brown and what can you do about it? Do all apples turn brown at the same rate? Let’s try to answer these burning apple science questions with an apple oxidation experiment that is pretty quick and easy to set up at home or in the classroom. We paired this with our Apple 5 Senses Activity.

WHY DO APPLES TURN BROWN FOR KIDS

Apple Science Lemon Juice Experiment for Fall STEM

APPLE SCIENCE ACTIVITIES

All this week we are going to be enjoying real apple science activities while we practice reading one of our favorite Fall books, Ten Apples Up on Top by Dr. Seuss. You can check out more Ten Apples On Top Activities.

BROWN APPLES

Ever found a bad spot on an apple or opened a container in a lunch box filled with apple slices that were once pearly white and now look a bit on the used up side. The bad spot is definitely not tasty but the slightly browned apples aren’t all that bad.

Is it safe to eat brown apples? My son tasted the brown slices of his favorite apple, the honey crisp, and declared them still ok. Not all apples are similar in their rate of browning!

How do you keep apples from turning brown? Lemon juice is often suggested as a solution for keeping apples from turning brown. Does lemon juice really work and how does it stop or slow the browning process?

Let’s try a simple apple browning experiment and find out!

Apple Science Experiment with Lemon Juice

There’s great science behind the process of why an apple turns brown or why rotten spots are brown. The simple science is that when an apple is damaged, or even cut into slices, the enzymes in the apple react with the oxygen in the air, which is called oxidation. The apple produces melanin to protect the apple which is the brown you see.

We watched this short video on Why do Apple Turn Brown? which digs deeper into the exact science of polyphenol oxidase (PPO) enzymes. It’s a mouthful!

HOW DOES LEMON JUICE STOP APPLES FROM BROWNING?

Lemon juice helps keep the apple from turning brown because it is full of ascorbic acid (Vitamin C) and it has a low (acidic) pH level. Ascorbic acid works because oxygen will react with it before it reacts with the polyphenol oxidase enzyme in the fruit.

APPLE OXIDATION EXPERIMENT

This is a great experiment to set up using the scientific method for kids. Also, print out our free science worksheets to record your observations. This experiment would also make for a cool why do apples turn brown science project.

YOU WILL NEED:

Apples! (We used 5 varieties of apples since we had just completed our apple 5 senses science activity beforehand.)
Lemon Juice {or real lemon}
Paper Plates, Knife, Small Cups {optional}
Printable Journal Page

Click here to get your FREE apple experiment worksheets!

APPLE EXPERIMENT SET UP

1: Label paper plates with the name of each type of apple you are using.

2: Then cut two wedges of the same size out of each apple.

3: Place one wedge in a small dish and the other on the plate alongside the rest of the whole apple.

4: Squeeze a little lemon juice over each slice in the dishes and mix to coat evenly. Dump out excess juice. Do this for each apple.

Apple Science Lemon Juice Experiment for Kids Fall STEM

5: Now wait and be patient. Record your observations.

If you want, set out a timer to get an accurate measurement of the time it takes for each apple to turn brown. This way you can record results in number of minutes for drawing conclusions later.

APPLE EXPERIMENT RESULTS

Which apple turned first?
Did they all turn equal shades of brown?
Does the apple slice coated in lemon juice taste different than the plain apple slice?
Does the brown apple slice really taste all that bad?
Did the lemon juice really work?

BELOW WAS OUR QUICKEST TURNING AND DARKEST BROWN SLICE.

He went on to happily eat both slices of cut apple and found them tasty. Fall is a great time of year for exploring apples!

Apple science lemon juice experiment why do apples turn brown?

APPLE OXIDATION EXPERIMENT VARIATIONS

We investigated whether lemon juice stops apples from turning brown in the experiment above. Why not extend the learning and compare different ways to prevent cut apples from browning.