How do you keep apples from turning brown? 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. Pair it with other fun apple science experiments!
Apple Oxidation Experiment
This is a great experiment to set up using the scientific method for kids. Use our printable apple browning experiment worksheet below to record your observations.
The independent variable will be the type of apple, and the dependent variable will the amount of lemon juice you add to each apple. Can you think of any other dependent variables?
Supplies:
- 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 (optiona)
- Printable Journal Pages (see below)
Set Up:
STEP 1: Label the paper plates with the name of each type of apple you are using.
STEP 2: Then cut two wedges of the same size out of each apple.
STEP 3: Place one wedge in a small dish and the other on the plate alongside the rest of the whole apple.
STEP 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.
STEP 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.
Our 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 APPLE 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!
Why Do Apples Turn Brown?
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 a process called oxidation. The apple produces melanin to protect the apple which is the browning you see.
We watched this short video on Why do Apples 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. Learn more about the pH scale.
Ascorbic acid works because oxygen will react with it before it reacts with the polyphenol oxidase enzyme in the fruit. What else might prevent apples browning in a similar way?
Alternatives To Lemon Juice – Using the Scientific Method
The scientific method is a process or method of research. A problem is identified, information about the problem is gathered, a hypothesis or question is formulated from the information, and the hypothesis is tested with an experiment to prove or disprove its validity.
💡 READ MORE: The Scientific Method For Kids With Examples
In the experiment below, we investigated whether lemon juice prevents apples from turning brown. Why not extend the learning and compare different ways to prevent cut apples from browning?
You could also test…
- Ginger Ale
- Salt Water
- Ascorbic Acid Powder
- Plain Water
Helpful Science Resources
Here are a few resources to help you introduce science more effectively to your kiddos or students and feel confident when presenting materials. You’ll find helpful free printables throughout.
- Best Science Practices (as it relates to the scientific method)
- Variables In Science
- Observation In Science
- Science Vocabulary
- 8 Science Books for Kids
- All About Scientists
- DIY Science Kits
- Science Tools for Kids
More Fun Apple Science Activities
- Learn about the parts of an apple.
- Use our printable life cycle of an apple worksheets to explore how an apple grows.
- Develop your observation skills with an apple 5 senses activity.
- Set up this awesome apple volcano experiment.
- Enjoy balancing apples for simple Fall physics.
Printable Apple Project Pack
With more than 125+ pages of apple-themed projects, you can easily plan and prep an apple unit filled with hands-on learning. Suitable for both classroom and home use in grades Kindergarten through Elementary. Easy to adapt to a wide variety of ages and abilities with more or less adult supervision.
Note: We have additional Pumpkin and General Fall Project Packs (leaves).
- 20+ Apple theme science and STEM activities with printable sheets, instructions, and useful information using easy-to-source materials perfect for limited-time needs.
- Apple theme science activities include making apple oobleck, testing sink or float, exploring an apple volcano, apple and lemon juice experiment, and dancing apple seeds. Fun and simple physics and chemistry with apples!
- Apple theme STEM challenges include a variation of the classic spaghetti tower challenge with an apple theme, stacking 10 apples, building apple structures, and more!
- More apple activities for science include parts of an apple pack, how an apple grows, apple tallying and graphing , apple taste test activity, apple 5 senses activity, and more!
- Apple Picking STEM Story Adventure Pack with real-life STEM challenges to solve and supporting materials.
- NEW! Apple Themed Art Projects
- Supply lists for every project make setup simple!
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