Why Do Apples Turn Brown? Science Experiment
We’re having apple fever around here this week! But I’ve been hating how apples turn brown so quickly. Maybe not as much as my picky 3 1/2-year-old, but annoyed just the same… So we decided to test a bunch of those methods you see out there for keeping the apples looking fresh. And why not turn experimentation into a lesson? So we threw in some Scientific Method for kicks, too. Read on for a fun experiment for kids and what works best for keeping apple slices white.
This apple experiment is a great chance to teach the kiddos about the Scientific Method. Why should you bother? The method teaches kids and adults critical thinking and a framework in which to approach any problem, not just ones in science. You can follow along with the experiment and the method below. This is a great STEM activity you can do with ingredients right in your kitchen. With the kids home more these days, you’ll be glad you have this quick educational experiment you can pull out of your back pocket anytime!
Plus, to make it super easy for you, we pulled together a helpful lab worksheet, scientific method poster, and easy-to-follow (and print!) experiment instructions. Just fill out the form below and it will be emailed to you right away.
FREE! APPLE SCIENTIFIC METHOD EXPERIMENT AND PRINTABLE
Scientific Method Step 1: Ask a Question
We hate it when apples turn brown. For some reason, they just don’t seem as tasty as when you first bite into them. So our question is: What is the Best Way to Keep Apples From Turning Brown?
Scientific Method Step 2: Do Research About Why Apples Turn Brown
I thought it would help the process to first learn what makes apples turn brown in the first place. Essentially your apple is rusting in a process called oxidation. Once the apple is cut or bruised, oxygen in the air combines with iron in the apple to form iron oxides. Enzymes in the fruit (like polyphenol oxidase) make this process go faster. The oxidation process is also what causes metals to rust.
You can reduce browning by slowing oxidation in three different ways. 1) Cook the apples 2) reduce the exposure to oxygen or 3) reduce the pH of the fruit. Doing both by covering in an acidic liquid is the best way to keep apples from turning brown without cooking.
Scientific Method Step 3: Form a Hypothesis
It’s time to formulate a hypothesis… Before the experiment, ask the kids a couple of questions. Their opinions will be their hypothesis.
- Which method do you think will work the best?
- Which one do you think will taste the best?
Scientific Method Step 4: Design an Experiment
It seems like everyone has an idea of the best way to keep apples looking fresh! We asked our friends for ideas (ummm, I mean I looked on Pinterest.) Here’s what we tried… Be sure to add a control that will show you how the apple turns brown with no treatment. A control is the part of the experiment that tests what an apple would do naturally, without treatment.
- Honey (1 teaspoon honey mixed with 1 cup water)
- Lemon juice (1 teaspoon juice mixed with 1 cup water)
- Salt (1/2 teaspoon salt mixed with 1 cup water)
- Vitamin C (1 tablet crushed and dissolved in 1 cup of water)
- Lemon-lime soda
- Carbonated water (bubble water)
- Experiment Control (we used the apple core)
Now it’s time to try all of these ingredients.
- First set out 8 bowls big enough to cover the slice completely with the solution. Label each bowl so you don’t mix up the solutions.
- Make each of the solutions in a separate cup.
- Cut one apple into 8 slices of approximately the same size. If you use more than one apple, you’re adding variables to the experiment as some apples may brown at different rates than the others.
- Place an apple slice into each bowl. You can use the core as the control.
- Immediately cover with each solution, one per bowl.
Scientific Method Step 5: Record and Analyze Data
Now comes the waiting period. We checked after 5 minutes and decided to wait another 5 minutes before pulling the apples out of the solution. You can choose your own time period based upon how fast the apples are turning brown. Then:
- Pour off the solution and inspect each apple for brown color. Record levels.
- Taste apples and record impressions.
Our lab worksheet will make it super easy to record and analyze the data!
Scientific Method Step 6: Draw a Conclusion
To help draw a conclusion from the experiment, ask the kids:
- Which one tastes the best?
- Which ones kept the apples the whitest?
You and the kiddos should test this for yourself, but here’s what we found in the experiment:
- Plain water doesn’t work. Carbonated water is a touch better, but not that much. Plus it gives a slightly bitter taste to the apples.
- Salt keeps the apples really white, but yuck! did not taste good. Probably need to try this with less salt.
- Lemon juice works well too but also changes the flavor of the apples. Good for fruit salad, maybe not for plain apple slices.
- Vitamin C works just ok, but definitely not well enough to be worth the hassle of crushing tablets.
- The lemon lime soda worked too, but they tasted like apples soaked in soda. Duh, right? Too candy-like and not really that healthy, so out.
So the winner is…HONEY! The apples weren’t quite as white as with salt and lemon, but the taste was sooo yummy. Like unadulterated apples, just deliciously sweet ones.
Even More Fall STEAM Fun for Kids!
This fun science experiment is a sneak peek into the STEAM Explorers Fall issue!
Join us as we explore all things FALL with STEAM Explorers . Kids will love learning physics with football, doing a leaf color-changing experiment, snacking on apple chips, exploring the beauty of sunflowers, and more! You'll love the helpful standards-based learning, printables, and tools that make STEAM (science, technology, engineering, art, & math) exploration easy!
32 thoughts on “Why Do Apples Turn Brown? Science Experiment”
Great experiment idea! It’s simple enough for little ones, and tasty too! Thank you for featuring me this week!!
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This is a great experiment. I know that apples turn brown based on oxidization.
Thanks so much! Glad you enjoyed it.
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I love your experiment and the look on your sweet girl’s face with the “HMMM.” And good to know – honey!!! We also tried lemon juice in the past but then my son wouldn’t eat them because like you said – flavor!!
Thanks Kristi! I had to put the hmmm… picture in. It’s one of my favorites :)
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Great experiment!! I did this with my 4 year old. We though honey tasted amazing to the rest!!! Salt was our whitest…..but our tap water was actually whiter in comparison to most..makes me wonder what is in our tap water….hmmmm…another project on the horizon. :) Thanks again!
That definitely makes me curious about your water!! Thanks for stopping by :)
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VanCleave's Science Fun
Your Guide to Science Projects, Fun Experiments, and Science Research
Browning Apple: Experiment
By Janice VanCleave
For this example science fair project the example question and hypothesis are:
What effect does the type of citric fruit covering apple slices have on their browning ?
Hypothesis:
Since all citric fruits contain citric acid, any kind of citric fruit covering apple slices will prevent the slices from browning.
Purpose: To determine if any type of citric fruit will prevent apple slices from browning.
IMPORTANT: You must test each acid the same way. Same kind of apple slices, same amount of acid for each test ETC…. These are things that might affect the results so you need to control them–that is you need to make them all the same.
Things to consider:
(1) Types of citric fruit.
(2) How to extract the juice from the fruit.
(3) How the juice will be applied to the apple slices. How much juice will be applied to each slice?
(4) Type of apple that will be used. Must use only one type.
(5) How thin the slices of apple will be. How many apple slices? I suggest 5 for each test.
(6) What will the apple slices be placed on and how will they be placed. I suggest that the slices be flat with one side facing up. Do not overlap the slices.
(7) How to label the different tests.They all need to be in the same place.
(8) Where the testing materials will be placed.
(9) DATA: How often you will make your observations.
(10) How you will evaluate the results–in other words, how you will decide if an apple has browned. In other words, will any browning no matter how slight be considered a positive test for browning?
(11) Don’t forget your control– This is the next step in the teacher tips list. Send comments and suggestions to ASK JANICE
RETURN TO SCIENCE FAIR PROJECT TEACHING TIPS for the next step
Share this:
Apple Oxidation Experiment
Introduction: Apple Oxidation Experiment
In case the video does not load, in order to watch paste the following link into your web browser: https://youtu.be/ldLxmkIWWZs
Step 1: Problem or Purpose
A problem that many people are facing is that their apples are browning quickly once they slice them into different slices and our experiment will conclude the best drink that keeps your apple slices fresh for the longest period.
What is the effect of different drinks on a slice of an apple?
Step 2: Hypothesis
If we add a slice of an apple in different drinks, the time taken for this slice to change color into brown will be different, because apples react differently with different types of drinks whether it was an acidic drink or a basic drink.
Step 3: Variables
Independent: the drinks we will add the apple slices into
Dependent: time taken for the slice to turn brown
Controlled: The freshness of each apple before we start the experiment, the type of apple (red apple), the temperature of the drinks and apples, amount of time to check on the apple slices.
Step 4: Background Research
What causes the apple to start bruising or turn brown is when it is exposed to oxygen, like when it is cut into slices, which causes apple oxidation. Some of the different materials and fluids used to prevent the browning of an apple are lemon juice, water, vinegar, and many more acidic drinks.
Step 5: Materials
1.4 containers
2.Diet 7up, Lemon juice, Low-fat Milk, Coke (1/4 cup each)
3.4 slices of apples
4.Camera/phone
6.Knife to cut apple
7.Measuring cup
Step 6: Procedure
1.Measure the drinks and pour about ¼ of the drinks into each container
2.Slice the apple
3.Place each slice of the apple into the container filled with the drink
4.Set a timer for 2 hours
5.Take notes of the apple with a picture of the slice every 30 minutes
6.After 2 hours have passed, take notes of the apple slice
7.Taste the apple slice to see which one changed the most taste and smell-wise.
8.Fill in the table with the left information and results
Step 7: Data
Step 8: Data 2
Step 9: Graph
Step 10: Data Analysis
From our experiment, we found out that different drinks will cause each apple slice to take a different amount of time to rot, and change color.
After 30 minutes, the apple slice in the diet 7up started turning a bit yellow (Brown Intensity: 20%), tastes like sweet lemon, smells like an apple with a bit of lemon. The apple slice in the lemon juice still looks the same (a white pale color) (Brown Intensity: 10%), tastes like a normal apple, smells like a normal apple. The apple slice in the milk was completely pale white (Brown Intensity: 10%), It tasted like an apple and there was no taste or smell of milk. The apple in the coke started turning brown (Brown Intensity: 30%), it did not taste like an apple but a strong flavor of coke, it smelled like coke and you can hardly smell the apple.
After 60 minutes, the apple slice in the diet 7up became a little more beige looking, (Brown Intensity: 40%), tastes like sweet lemon with a bit of fizz coming from the carbonated soft drink, smells more like a sweet lemon. The apple slice in the lemon juice has barely turned yellow (Brown Intensity: 20%), smells a little bit like lemon, has a hint of sourness. The apple slice in the milk was still completely white (Brown Intensity: 10%), tasted a bit like milk but mostly like an apple, you can hardly smell the milk. For the apple in the coke, it started turning brown (Brown Intensity: 50%), the apple took the taste of the coke and the taste got stronger, it started to smell like coke.
After 90 minutes, the apple slice in the diet 7up started turning a little brown (Brown Intensity: 43%), tastes very soft, also like lemonade with apple, smells a little like 7up and lemons. The apple slice in the lemon juice has started turning yellow (Brown Intensity: 35%), tastes very sour and lemony, smells a lot more like a lemon. The apple in the milk, was still white (Brown Intensity: 10%), the slice slightly tasted like milk but more like apples, it smelled like a bit of milk with apple juice. The apple in the coke’s color was dark from the amount of coke it absorbed (Brown Intensity: 70%), the taste of the coke is extremely clear and you can barely taste the apple, it smelled like coke and a rotten apple.
After 120 minutes, the apple slice in the diet 7up is a light brown (Brown Intensity: 45%), the apple slice is very soft and sweet and took the taste of the diet 7up, smells a lot like 7up and lemons. The apple slice in the lemon juice apple is still the same shade of yellow and has not darkened much (Brown Intensity: 40%), tastes a lot sourer, smells like lemons or lemon juice. The apple slice in the milk’s color was white and did not change at all (Brown Intensity: 10%), it tasted just like an apple with a little stronger taste of milk, it smelled like an apple mixed with milk.
Step 11: Data Analyisis 2
A few mistakes someone can make while conducting this experiment are: using a rotten apple while starting this experiment, using a different colored apple for every drink (when the controlled variable is using the same type of apple), placing the apple and its drink in different weather climates, not putting enough of the drink so it can cover the apple to be able to see some results, etc.
A few ways I can make my experiment better: use apples grown in different locations and places, use red and green apples to see the difference between them, keeping the apple slice in the drink in the fridge or at a hotter temperature to see the difference, etc.
1. This experiment is a solution to a big problem many people face, which is having their apples rot quickly.
2. This experiment was a successful experiment since we ended up with suitable results that can help others.
3. This experiment was done in real life and not digitally so we are sure that the results we ended up with are realistic and true.
Weaknesses:
1. A weakness is that the apples may have shown results if we kept them in the drinks for a longer amount of time.
2. The results may not be as accurate, because there are two different experiments placed in different cities, there is a chance that the weather and climate have an effect on the results of each experiment.
3. Putting an apple slice in a liquid may not be the best solution to keep your apples the freshest since it may not be suitable for kids in school or people transporting from a place to another, since they may not have all the materials and supplies needed.
Step 12: Conclusion
In our experiment, we tested the effect of different drinks on the rotting of an apple. Our hypothesis was correct since the apples were differently affected by the drink, they were put in. Our variables were: Independent, the type of drink, Dependent: the freshness of an apple. Controlled: the type of apple (red apple), the freshness of the apple when we began the experiment, the temperature of the experiment (room temperature). In conclusion, the lemon and the milk did the best job in this case, however, the apple slice that was put in the lemon eventually tasted and smelled only like a lemon. Therefore, milk is our suggested drink for people to use in order to keep the apples fresh since it made the apple stay the freshest and smelled and tasted more like an apple whereas the apple slices in the other drinks took the taste of the drinks and rotted quicker. In addition, milk will preserve the apple from getting brown because it's a basic liquid.
Step 13: Application
Our experiment is important because there are many people who enjoy only a piece of their apple but do not want to complete the whole thing. But the only problem is that when oxygen meets the apple, the apple starts to brown. And we were curious to find a way to avoid this from happening. So, we conducted an experiment, to find out which drink does the best job to keep the apple slice the freshest. Yes, this experiment can be applied with practice to do it correctly without making any mistakes in order to keep your apple slices fresh. After this experiment, we learned that milk and acidic drinks are the best drinks to keep your apple from browning. In addition, milk is the least drink that the apple took the drinks taste and smell.
Step 14: Evaluation
- Dima: during this project, I have represented a few of the ATL skills. Some are; researching skills, communication skills, thinking skills, self-management skills. I have shown research skills because once we started using different applications such as Instructables, I researched and learned how to properly use it to make sure I submit my assignments properly, as well as, at the beginning of the project we were asked to research our problem, and there I have collected a lot of information online. I have shown communication skills , because, throughout my work in a group, I made sure to stay in contact with my group members to see if I should help them with anything, also to get to know their ideas and opinions about what we are doing. I have also shown thinking skills because in the science fair I thought creatively about unique and different ways to complete my tasks. In addition, when I faced a problem I made sure to think about how I am going to solve it. Lastly, I have shown self-management skills since I submit all my tasks on time and I complete them correctly and the way I was asked to. I depended on myself and I was responsible throughout this project.
Allya: research skills, I feel like we used research skills because we researched about our experiment at the beginning to know what the experiment is about. Social skills, I feel like we used social skills because I and my teammates were communicating together during school hours and after school. Self-management, there was some work that I had to do individually so I depended on myself and I did the work myself me and my group collaborated together. Thinking skills, my group and I thought creatively while making the experiment during the hypothesis and the rest of the steps.
Sadeem: Social skills, I used my social skills to communicate with my group members. Self Management Skills, I used my time wisely and tried to stay free in case the group members needed me. Thinking skills, I used thinking skills to find some solutions to our problems and to find answers to my questions. Research skills, I researched why lemon juice made the apple turn out how it is, and in the background research step, I also used my researching skills in order to find answers to my questions.
Step 15: Resources
Source #1: How to keep apples from Browning? Here are 6 tricks we love. (2020, June 12). Retrieved from https://www.purewow.com/food/how-to-keep-apples-f...
Source #2: Why do apples turn brown? (2021, January 22). Retrieved from https://miniyummers.com/why-do-apples-turn-brown/...
Source #3: Prakash, S. (2019, September 24). The easiest ways to keep your apples from Browning. Retrieved from https://miniyummers.com/why-do-apples-turn-brown/...
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