formulate your hypothesis in apple turning brown

VanCleave's Science Fun

Your Guide to Science Projects, Fun Experiments, and Science Research

Browning Apple: Hypothesis

By Janice VanCleave

If your science fair project question is:

What effect does the type of citric fruit covering apple slices have on their browning ?

Your hypothesis will be your idea about the answer to your science fair project question. A hypothesis is basically your educated guess. A hypothesis is your prediction about the results of the experiment you will do to find the answer to the project question. Your hypothesis should be based on facts.

HYPOTHESIS EXAMPLE :

Since all citric fruit contains citric acid, then covering apple slices with the juice of any type of citric fruit will prevent the slices from browning.

Your next step in developing your science fair project is to design an experiment which tests the accuracy of your hypothesis.

Designing an Experiment

Another import part is having an experimental control. Experimental Control

Send comments and suggestions to ASK JANICE

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Published: Aug 23, 2021 · Modified: Mar 26, 2024 by Julie

Apple Science Experiment with Worksheets

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Have you ever sliced an apple, only to find it has quickly turned brown? In this apple experiment, kids will observe how different liquids effect the process of apple browning.

Practicing science is fun and hands on with this classic science experiment!

• Science Concepts

If you are learning about science with your kids, simple science experiments are a fun way to practice the scientific method . One of the best ways to test out a hypothesis is through a hands on exploration.

This Post May Contain Affiliate Links. Please Read Our Disclosure Policy .

Why Do Apple Slices Turn Brown After being Cut?

Recommended age range, apple oxidation experiment worksheets, preparation, optional liquids, helpful hints, the science behind apple browning, concept of apple browning, more apple activities and project ideas, comparing different varieties of apples, storing in a plastic bag vs no bag, other browning fruits.

In this apple science experiment, kids will learn about the process of oxidation. Depending on the age of your kids, you can modify how much of this experiment they set up and run on their own.

A great activity to go along with this is to do an apple exploration with your kids to learn about the different parts of an apple.

If you are looking for ways to explore apples with your kids, check these additional apple activities for kids .

The great thing about experimenting with kids is that you can take a lesson and modify it to fit your needs.

If your child is practicing identifying variables and designing an experiment, they can be in charge of that part.

While for younger kids, you can provided a more guided approach.

When doing this with elementary aged kids, you can have them pick the liquids, help cut up the apples, and run the timer.

Younger kids can make observations, pour liquids, and drop the apple slices into the different containers.

Kids of all ages love having jobs, especially when running an experiment. Before you begin, decide who will be in charge of each task. Don't forget about clean up! Kids can be in charge of putting back supplies or washing containers.

Apple oxidation, commonly called browning, happens after an apple is sliced or damaged. Various liquids can be used to slow down apple browning. ( source )

If you are doing this apple experiment with young children that will be enough of an explanation. However, a description of the process along with vocab terms if doing this with older children can be found later on in the post.

More Autumn Activities: Painting with Apples and Fall Leaf Printables

• Middle School

If I was going off of the description above I would say, middle school aged kids. But honestly, young kids even preschoolers will enjoy this experiment.

What is great about this science experiment is that you can tailor it to fit your child's needs.

Remember, you do not need to explain all of the fancy scientific concepts that are found later on in the post.

Lab sheets are great for elementary and middle school aged kids. Young children can simply discuss the changes you see.

There is also a guided version of the worksheet available for download as well. This version has some of the parts filled out for your child.

Directions for how to access the downloadable free printable worksheets is found at the bottom of this post.

Before beginning this experiment you will want to gather a few supplies. First make sure you have apples! Depending on how many kids are doing this experiment will determine the amount of apples you need.

One apple is more than enough if you are doing it at your house with your kids.

If trying this out with a larger group, I would plan on having a few apples. I try to not be wasteful with food, so I sliced the apples very thinly.

Before doing the experiment with your kids, I would go over the directions, fill out the lab sheet, and talk about what you will be doing. Then begin the experiment with your kids.

Often times kids are so excited to get started that they miss out on practicing important science skills such as identifying variables and making a hypothesis.

Slicing the Apples

You will also need a safe way to cut the slices using either a knife or apple corer. I used a knife with a cutting board and cut the apples for my child.

Picking Out the Different Liquids

For this apple experiment, your kids will be testing out different solutions to see how well they prevent browning of the apple pieces.

Pick out the different liquid substances before beginning this science project. You will also need containers to hold the liquids, I used small glass Pyrex containers .

After the materials list below, I give you a few recommendations for liquids.

As you can see from the image above, I used salt water, apple cider vinegar, freshly squeezed orange and lemon juices, and plain water.

• 1 Container per Liquid
• 1 Lid per Liquid
• 1 Toothpick per Liquid
• 1 Knife or Apple Corer
• Cutting Board
• 4 or More Liquids
• Water (Control)
• Flat Work Surface
• Recording Sheet
• Optional: magnifying lens

All of these directions can be found on the downloadable lab sheet. Even if you do not use the sheet with your kids, it may be helpful to have printed directions.

• Gather supplies and pick out your liquids
• Set out one container per liquid on a table.
• In front of the container place a lid (this will hold the apple slice)
• Add labels in front of each lid with the name of the liquid or place the main container of the liquid behind the set up. You want to easily see which liquid was used for each slice.
• Add a small amount of each liquid into each of the containers. Enough liquid to coat the slice once it is placed in the liquid.
• Prepare your apple slices using a knife or apple corer. *As the adult, I cut the apples
• Add one apple slice into each of the liquids. Set the timer for 1 minute. Remove the apple slices from the liquids using a toothpick. Place slices onto the lids.
• Reset the timer for the next length of time then make your observation.
• Record observations for one minute, 10 minutes, 20 minutes, and 40 minutes.
• Compare your final results after 40 minutes to the control. Record which liquid prevented the apple slice from browning the most.
• Clean up the experiment. Then write your analysis and conclusion.

If you do not have lids available, parchment paper or plates can be used. I would not recommend placing wet apples directly onto a paper towel because the liquid can saturate the towel.

You can use more than four liquids, just make sure to plan one lid and glass container per liquid. Water will be the control which also needs a lid and container.

When I ran this experiment with my child, we used plain water as the control apple. However, I noticed the apple left out without being dipped into the water showed more signs of browning.

I recommend leaving a slice out on the table that never is dipped into a liquid. Kids can compare the results to that apple as well!

Now the fun part, the science behind why apples turn brown. Depending on the age of your child will determine how in depth you want to explain this process.

I broke up the vocab terms into simple and advanced.

However, you can do this fun science project without explaining all of the fancy science terms! I included them in case you want to go that route with your kids. Some kids love knowing the why behind what they are seeing.

Simple Vocab Terms

• apple or fruit
• guess or hypothesis
• observation

Advanced Vocab Terms

When apples turn brown, they are undergoing a chemical change as the slices are exposed to air.

If you happen to have older kids, they could also do this experiment along with researching the advanced vocab terms.

The source listed above has some great information about the process of apple oxidation.

The best thing about practicing science with kids is tapping into their natural gift of curiosity. Kids come up with the best ideas as they question how the world works.

Use one or all of these lesson extensions to explore more about apples with your kids.

Always make sure to have a control group so that you are conducting a true science experiment. Plan out the experiment using the scientific method before beginning.

It would be so much fun for kids to test out different kinds of apples. They can use the best liquid found from this experiment.

This is a great way to test out how well it works at keeping different kinds of apples from turning brown.

After doing the initial experiment your kids may wonder if the kind of apple will effect the browning process.

Many stores sell pre-sliced apples in plastic bags. With this fun experiment, have your kids test to see how apples placed in plastic bags compare to ones being left out in the open.

For a fun variation, kids can test to see if flattened out bags with most of the air removed will effect browning.

They can compare the results of flattened bags to ones having a large amount of air left inside.

Conduct an easy experiment similar to the apple science experiment. Have your kids brainstorm then pick out a few other fruits that also brown once sliced.

If they are not sure if any other fruits change color they can do a science project where they slice a variety of fruits and observe the changes in color.

Then they can test out different liquids and record the results. It would be fun to see if the same liquids had similar results for different fruits.

Make sure to download your free copy of the apple experiment below!

Terms of Use

These worksheets were created by  Nature Inspired Learning  and are for  personal use only for your home, classroom, or public library see full disclosure . All of these apple experiment worksheets are for  non-commercial use .

Two different versions: a guided version and a blank activity sheet.

More Easy Science Experiments

Reader Interactions

Ashley says

October 28, 2021 at 10:22 am

Oh my kids will love this! Thanks for all the information. Can’t wait to try it!

October 30, 2021 at 1:17 pm

Your very welcome Ashley, I hope your kids enjoy the experiment

Mikaela says

October 28, 2021 at 10:36 am

What a fun experiment! I am going to have to do this with my class!

Awesome! I hope they enjoy conducting the experiment

October 28, 2021 at 11:51 am

You have so many great tips for doing this experiment! Great idea!

Thank you Laura

Kelsey says

October 28, 2021 at 4:22 pm

So many great ideas here that anyone could do! Thanks for sharing!

October 30, 2021 at 1:18 pm

Thank you Kelsey! Yes easy to do even as a spur of the moment activity when cooking with apples

October 28, 2021 at 7:39 pm

I love this apple science experiment! It is a fun way to learn science. Thank you so much for sharing!!!

October 30, 2021 at 1:19 pm

Your very welcome Ada

January 22, 2023 at 11:15 pm

My children love apples. These will be so fun! Julie, on these cold days, do you know how to make fake snow ? Cindy

January 23, 2023 at 11:14 am

I'm not sure about how to make fake snow possibly with baking soda and water (however it wouldn't be safe to eat)? Or if you are able to use a mini snow cone machine that grinds up ice to make "snow" that would be fun too!

Farren says

August 28, 2023 at 3:30 pm

I'd love the Apple Oxidation Lab freebie, thanks!

August 28, 2023 at 3:34 pm

Hi Farren, There is a sign up form at the end of the post for a PDF version of the activity sheets. Best, Julie

Stacey says

September 04, 2023 at 8:21 pm

I love this so much!

September 05, 2023 at 6:09 am

Hi Stacey! Enjoy, happy exploring

Josie Heflin says

September 17, 2023 at 11:10 pm

I'm super excited to do this with my son!!! Thank you so much for this!!!

September 23, 2023 at 9:35 am

You're very welcome! I hope you both have fun.

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Apple Browning Experiment

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!

Try This Apple Browning Experiment For Fall

Have you 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 experiment and find out how to stop apples from browning!

Using The Scientific Method With Kids

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.

Sounds heavy! What in the world does that mean?!? It means you don’t need to try and solve the world’s biggest science questions! The scientific method is all about studying and learning things right around you.

As children develop practices that involve creating, gathering data evaluating, analyzing, and communicating, they can apply these critical thinking skills to any situation.

READ MORE:   The Scientific Method For Kids With Examples

Note:  The use of the   best Science and Engineering Practices   is also relevant to the topic of using the scientific method. Read more and see if it fits your science planning needs.

Helpful Science Resources To Get Your Started

Here are a few resources that will help you introduce science more effectively to your kiddos or students and feel confident yourself 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

Set Up An Apple Browning Science Project

Science projects are an excellent tool for older kiddos to show what they know about science! Plus, they can be used in all sorts of environments including classrooms, homeschool, and groups.

Kids can take everything they have learned about using the scientific method , stating a hypothesis, choosing variables , making observations and analyzing and presenting data.

Want to turn this apple oxidation experiments into an awesome science fair project? Check out these helpful resources.

• Science Project Tips From A Teacher
• Science Fair Board Ideas
• Easy Science Fair Projects

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

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

You could also test…

• Ascorbic Acid Powder
• Plain Water

Get your printable apple experiment worksheet!

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?

• 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

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!

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 Preschool Apple Activities Pack

Get ready to explore this year with our growing Preschool STEM Bundle !

What’s Included:

There are 5 fun preschool themes to get you started. This is an ” I can explore” series!

• My 5 Senses
• All About Me
• Science and Scientist

Each unit contains approximately 15 activities, with instructions and templates  as needed. Hands-on activities are provided to keep it fun and exciting. This includes sensory bins, experiments, games, and more! Easy supplies keep it low cost, and book suggestions add the learning time. 

Or grab the Apple Preschool Pack on it’s own!

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Differentiated and Visual Supported Resources for Special Education

Apple Experiment: Why do apples turn brown?

Back to School Season is always a good time to do an Apple Theme! This year we kicked off the school year with some fun apple science to get our brains warmed up! Why do our apples turn brown after we cut them if we don’t eat them fast enough?! AND can we prevent this from happening? Let’s experiment!

First, we had a big discussion about why our apples turn brown. We found some great videos on YouTube that help explain apple browning in kid friendly terms. Search “Apple Browning for kids” on YouTube to find a video that works best for your students! My favorite video is “Why Do Apples Turn Brown?” by SciShow Kids.

Then, we followed the 5-Step Scientific Method to conduct our experiment. CLICK HERE for a FREEBIE set of Scientific Method Posters I use in my classroom.

What we know:

We can eat apples! Apples are a healthy snack.

Sometimes if we don’t eat an apple right after we cut it, the apple turns a little brown.

The apple’s skin protects the fruit on the inside. Once the skin is broken or the apple is cut, the fruit on the inside is exposed to oxygen.

Apples contain ENZYMES in the fruit that help it live. Once the ENZYMES are exposed to oxygen they react by turning brown. This is called OXIDATION. Some liquids contain absorbic acid, or Vitamin C, which have a low PH level. These liquids can delay the OXIDATION process because the enzymes in the apple will not be activated when mixed with a low PH level.

Not all liquids have the same PH level. Only liquids with a low PH level will delay the OXIDATION process and slow down the apple from turning brown.

What we need:

1 Apple, 4 Paper Plates, Knife, Lemon Juice, Milk, Water

Let’s Experiment!

CLICK HERE for a Ready-To-Go, picture-supported experiment packet for your students!

Step 1: Ask a Question

Which liquid will prevent the apple from turning brown?

Step 2: Make a Guess

Milk? Lemon Juice? Water? None of them? 🤔

Step 3: Do the Experiment

Label each plate with the liquid cards.

Cut the apple into 4 slices.

Put one apple slice on each plate.

Before adding liquid to the apples, record Observation 1 in your Apple Observation Booklet.

Pour a spoonful of each liquid on the corresponding plate.

Set the timer for 30 minutes. Record observations. Repeat 1 more time.

Step 4: Collect Data

We recorded our observations in my our Apple Observation Booklets. (CLICK HERE to check it out – it is full of differentiation and picture-support for students with multiple abilities) OR students can create their own Apple Observation Booklets depending on their abilities.

Step 5: Conclusion

We found the LEMON JUICE prevented the apple from browning the most. All the apples did eventually brown, but at different times.

To further extend the activity, send your students home with this question!

Can you think of any other foods that start to brown when they are exposed to oxygen? Try this same experiment with other foods. Avocado? Banana? Potato?

More Apple Activities…

Caramel Apple Recipe and Sequencing for Special Ed

More or Less Apples in the Basket? BOOM Cards™

Picture Matching Task Cards: Apple Theme

Where is the apple? Positional Word Game

Interested in some other fun, picture-supported science experiments?

CLICK HERE to check out my Fall Pumpkin Experiment: Do Pumpkins sink or float?

Check out some of my other Science Experiments in my TPT Shop:

Thanks for reading!

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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!

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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Why Do Apple Slices Turn Brown?

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• Ph.D., Biomedical Sciences, University of Tennessee at Knoxville
• B.A., Physics and Mathematics, Hastings College

Apples and other produce (e.g., pears, bananas, peaches) contain an enzyme called polyphenol oxidase or tyrosinase. When you slice open or bite into a piece of fruit, this enzyme reacts with oxygen in the air and iron-containing phenols that are also found in the fruit. This oxidation reaction causes a sort of rust to develop on the surface of the fruit. You will notice browning whenever a fruit is cut or bruised because these actions damage the cells in the fruit, allowing oxygen in the air to react with the enzyme and other chemicals inside.

The reaction can be slowed or prevented by inactivating the enzyme with heat (cooking), reducing the pH on the surface of the fruit (by adding lemon juice or another acid ), reducing the amount of available oxygen (by putting cut fruit under water or vacuum packing it), or by adding certain preservative chemicals (like sulfur dioxide). On the other hand, using cutlery that has some corrosion (common with lower quality steel knives) can increase the rate and amount of the browning by making more iron salts available for the reaction.

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July 30, 2007

Why do apple slices turn brown after being cut?

Getty Images

Lynne McLandsborough, a professor of food science at the University of Massachusetts Amherst, explains this oft-observed kitchen conundrum.

When an apple is cut (or bruised), oxygen is introduced into the injured plant tissue. When oxygen is present in cells, polyphenol oxidase (PPO) enzymes in the chloroplasts rapidly oxidize phenolic compounds naturally present in the apple tissues to o-quinones, colorless precursors to brown-colored secondary products. O-quinones then produce the well documented brown color by reacting to form compounds with amino acids or proteins, or they self-assemble to make polymers.

One question that often accompanies yours is, "Why do some apples seem to brown faster than others?"

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Well, nearly all plant tissues contain PPO, however, the level of PPO activity and concentration of substrate--here, the phenolic compounds--can vary between varieties of fruits (say, Granny Smith versus Red Delicious). In addition, a tissue's PPO level can vary depending on growing conditions and fruit maturity. One approach the food industry employs to prevent enzymatic browning is to select fruit varieties that are less susceptible to discoloration—either due to lower PPO activity or lower substrate concentration. This approach, however, may not be practical for the home "culinary scientist."

In the home kitchen enzymatic browning can be prevented by either reducing PPO oxidation activity or lowering the amount of substrate to which the enzyme can bind. Coating freshly cut apples in sugar or syrup can reduce oxygen diffusion and thus slow the browning reaction. Lemon or pineapple juices, both of which naturally contain antioxidants, can be used to coat apple slices and slow enzymatic browning. In addition, both fruit juices are acidic and the lower pH that they bring about causes PPO to become less active. Heating can also be used to inactivate PPO enzymes; apples can be blanched in boiling water for four to five minutes to nearly eliminate PPO activity. (Be warned that cooking will affect the texture of the product.)

Enzymatic browning is not unique to apples. PPO—a mixture of monophenol oxidase and catechol oxidase enzymes—is present in nearly all plant tissues and can also be found in bacteria, animals and fungi. In fact, browning by PPO is not always an undesirable reaction; the familiar brown color of tea, coffee and cocoa is developed by PPO enzymatic browning during product processing.

What is the Hypothesis about the apple turning brown?

That the lime was going to help the apple from turning brown.

Add your answer:

What is an hypothesis for cutting an apple?

Hypothesis 1: When you disturb the skin of an apple by cutting the apple into half, the exposed area will turn brown due to exposure to air.Hypothesis 2: If you snugly wrap or cover the exposed area of an apple after cutting it (disturbing the skin), you can slow down how fast the inside turns brown. Hypothesis 3: If you remove all of the skin of an apple and let it sit in the air, the outside will turn brown but the inside will not turn brown at the same rate. Hypothesis 4: If you remove all the skin of an apple AND slice the whole apple into pieces, all sides exposed to air will turn brown; if some slices are thicker, the inside will turn brown more slowly than the exposed outside areas.

What is making a hypothesis?

Making a hypothesis is turning your question into an answer Example: you say "How is a rainbow made" you answer the best of your ability) "A rainbow is made by the sun reflecting on the water"

What happens to a sliced apple if it is put in a plastic bag for a week?

It will turn brown faster in the plastic bag than normally because it produces a chemical that makes it turn brown faster. That can be avoided if you put lemon juice on the apple.

A possible explanation or answer to a question is a?

A hypothesis

Can an apple melt?

No, the best you'll get is a heap of ash.

How do you write a hypothesis for how can apple slices keep from turning brown?

you don't

Is an apple turning brown a physical or chemical?

An apple turning brown is both a chemical and a physical change. Physically it changes appearance by turning brown. Chemically it oxidizes when the air comes in contact with the enzymes and chemicals in the fruit.

How do you keep apple cider from turning brown?

http://www.articlesbase.com/food-and-beverage-articles/keep-apple-slices-from-turning-brown-naturally-1238490.html

What gas is responsible for turning apple brow?

Oxygen. Dip apple slices in lemon juice to keep them from turning brown.

Can you use a hypothesis for this problem Which chemicals will keep the fruit from turning brown?

A hypothesis doesn't have to be a correct statement. Just pick a chemical and say this one will or will not keep the fruit from turning brown. Then give a brief statement about why you think this way.

Why does chilling an apple keep it from turning brown?

cause it gets pooped on

Will putting acids on an apple stop it from turning brown?

Putting acids on a apple will not stop it turning brown as the apple is an acidic fruit itself so adding more acid would make it turn brown quicker.If you wanted to delay the browning of an apple you can always try neutrelising the apple by milk or something neutrel .It may no taste that great though .

How would apples dipped in vinegar affect the apple?

it will stop them from turning brown

Is An apple turning brown and food burning on stove is this a physical change?

No, chemical.

Putting lemon juice on a piece of cut apple will?

Help prevent the cut apple from turning that nasty brown color.

Is an apple turning into apple juice a chemical change?

No, it would be a chemical if someone cut open a apple and left it on a table for 20 minutes then coming back and the apple being brown.

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Moderators: kgudger , Moderators

Post by lanesmom » Wed Mar 25, 2015 1:58 pm

Re: HYPOTHESIS

Post by SandbaggerOne » Wed Mar 25, 2015 9:53 pm

Post by lanesmom » Wed Mar 25, 2015 10:23 pm

Post by SandbaggerOne » Thu Mar 26, 2015 1:46 pm

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Apples: stop the browning, hours and location.

Have you ever wondered if there was something you could do to stop apples from turning brown after they’re cut? The good news is lemon juice will do the trick — but some people don’t like the taste of lemon-y apples. Are there any other ingredients in your kitchen that can keep apples in their original splendor? Become a food scientist at home and find out!

• One or two apples, cut into slices
• Lemon juice
• Two other edible, liquid ingredients of your choice (e.g., orange juice, honey)
• One edible powdered ingredient (e.g., baking soda, salt)
• Five sandwich bags
• A permanent marker
• Small pieces of paper
• A way to keep track of time

Instructions

• Set a few apple slices aside in a sandwich bag. These are your control — you won’t put anything on these.

• Make sure the apple slices are completely coated in the liquid. Next, remove them from the bags and lay them out on plates, with their labels. Lay your control apples out nearby.

• Give the apples a taste test! Which one do you find the tastiest? What are your conclusions?

Suggestions

• Keep the experiment going! See how long your apples slices stay white. Do they all eventually turn brown?
• Try using different apple varieties, comparing how much each one browns.

What’s happening?

An enzyme is like a little scissor that, in just the right conditions (such as when it touches air), can change the shape of other molecules.

When we cut an apple, oxygen from the air makes an enzyme in the fruit turn other compounds, called phenols, into melanin. Melanin is the same brown pigment as in our skin!

By blocking oxygen or making the conditions acidic, you prevent the enzymes from working. If the enzyme doesn’t work, it doesn’t transform the phenols. This keeps the apple white!

Educational Activity Kit: Apples Cold storage: Making the most of Your harvest

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