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Why Does Food Rot?

March 5, 2012 By Emma Vanstone 13 Comments

Why does food rot? Have you ever noticed that if you leave an apple (or any fruit ) for too long, it starts to rot or decay? This can lead to a lot of food waste, so it’s important to understand how to store food items so they last as long as possible.

Why does food rot?

Food rots because micro-organisms such as bacteria, yeasts and fungi feed on the fruit and break it down. Have you also noticed that keeping fruit and vegetables in a fridge makes them last longer? This is because the cold slows down the growth and reproduction of microorganisms, slowing their decay.

Rotting mouldy foods on a chopping board

How to preserve apples

This simple science activity investigates ways to stop apples from spoiling without a fridge!

preserve apple by keeping them in vinegar

What you need for an apple rotting experiment

4 containers
lemon juice
salt water ( 1 tablespoon salt dissolved in hot water )

Apple rotting investigation instructions

Cut the apple into 4 even pieces.
Place a segment of apple into each container.
Cover each apple with the same amount of either lemon juice, vinegar or salt water. Leave one just exposed to the air ( this is the control ).
Leave untouched for about a week in a cool place and observe the differences.

Apple rotting investigation results

Control Apple – y ou can see this has started to shrivel up, but there is not much evidence of mould.

Apples preserved with salt and vinegar ( vinegar is at the front )

Apple rotting experiment - apples left in vinegar

Apples preserved with lemon juice

How can you stop food from rotting?

There are many mechanisms for preserving food. All slow or stop the activity of micro-organisms which make the food decay.

As well as refrigeration, you can freeze, can or pickle foods to preserve them.

You can see from the photos that in our investigation, the apple segment in the salt is the best preserved. This is because salt draws the moisture out of the food, so the micro-organisms do not thrive and cannot reproduce as fast as they can in other conditions.

The vinegar did prevent mould growth. This is because vinegar has anti-microbial properties. It inhibits or kills the microorganisms that lead to mould on the surface.

You can see that the lemon juice shows evidence of mould. This could be because the micro-organisms have flourished in the sugary environment.

More food preservation ideas

Can you think of other things to try? What about bicarbonate of soda? Or other fruits?

The Free Range Life has some great ideas for preserving peppers you could test too!

More kitchen science experiments for kids

These egg experiments are fantastic fun!

Find out how to transform egg white into beautiful meringue !

child making merginue to learn about kitchen science

Make your own rock candy !

Or, go all out and have a Science Bake OFF !!

Last Updated on February 29, 2024 by Emma Vanstone

Safety Notice

Science Sparks ( Wild Sparks Enterprises Ltd ) are not liable for the actions of activity of any person who uses the information in this resource or in any of the suggested further resources. Science Sparks assume no liability with regard to injuries or damage to property that may occur as a result of using the information and carrying out the practical activities contained in this resource or in any of the suggested further resources.

These activities are designed to be carried out by children working with a parent, guardian or other appropriate adult. The adult involved is fully responsible for ensuring that the activities are carried out safely.

Reader Interactions

March 05, 2012 at 5:05 pm

Another great experiment. Thank you so much.

March 06, 2012 at 9:50 pm

I’m so glad you like them!

March 06, 2012 at 7:32 pm

ewwww, wouldnt have expected that with the lemon juice….the husband left an apple on the side in the kitchen when we went away for a week last August, considering the heat that our kitchen reaches (it’s also a conservatory) I feared the worst……and was surprised that it looked exactly the same as when we left! x

I know weird hey!

March 07, 2012 at 6:27 am

This reminds of the lyrics in the theme song for Sid the Science Kid 🙂 Cool idea. I’d have to make sure my son didn’t eat the experiment – mold and all!

March 08, 2012 at 10:57 pm

sounds like my son. 🙂

March 07, 2012 at 10:43 am

What a great experiment. Must try it.

March 07, 2012 at 6:30 pm

HA! I like Ali’s “Must try” comment above me.. though fascinating.. I am not sure I really want to try it… mouldy things.. yukky!

Thanks for sharing on Kids Get Crafty!

ha ha, that made me laugh Maggy!

March 10, 2012 at 11:00 pm

I remember doing a similar science experiment with bread in different conditions when in year 7 and then teaching the same experiment a umh number of years later – but this with apples would add a new spin on it.

Thank you for sharing with Tuesday Tots and look forward to seeing you again next week.

March 13, 2012 at 8:20 pm

Ugh that lemon juice one is icky. I guess I’m still finding enough things like that by accident from forgetful kids that I”m not quite ready to try it 🙂

September 21, 2018 at 12:18 pm

I tried this and got opposite results. I set it up exactly like you said and showed in your pictures. My salt water apples were by far the WORST! And my lemon juice apples were the best. My science biology teacher friend explained that the acid in the lemon juice and vinegar prevents mold better. The salt pulled the sugary juice from the apple and bacteria (mold) formed on that.

November 30, 2019 at 7:13 pm

This helped me so much with my science fair project thank you . You are a life saver.

The Rotting Apple Experiment: A Fun Science Activity for Kids

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Are you looking for an exciting and educational science experiment to do with your kids? Look no further than the Rotting Apple Experiment! This hands-on activity is perfect for homeschoolers, curious young scientists, and anyone interested in exploring the fascinating world of decay. Let’s dive into this engaging experiment that will teach your children about food preservation, microbiology, and the scientific method.

Why Does Food Decay?

Have you ever wondered why that forgotten apple in your fruit bowl starts to shrivel and turn brown? It’s all thanks to the tiny microorganisms that surround us! Bacteria, fungi, and yeasts feed on fruits and vegetables, breaking them down in a process we call decay.

But here’s an interesting fact: fruits and veggies that are kept in the refrigerator stay fresher longer. Why? The cold temperature slows down the growth and reproduction of those pesky microorganisms, putting the brakes on decay.

The Rotting Apple Experiment: What You’ll Need

Ready to see decay in action? Gather these simple materials:

Four clear containers

How to Conduct the Rotting Apple Experiment

Follow these easy steps to set up your experiment:

Cut and core the apple into four equal segments.
Place each apple segment into a separate clear container.
Container 1: “Air” (leave the apple slice exposed)
Container 2: “Vinegar” (submerge the apple slice in vinegar)
Container 3: “Water” (completely cover the apple slice with water)
Container 4: “Oil” (submerge the apple slice in oil)
Observe and record changes in each container daily.

A Glimpse at our results from The Rotting Apple Experiment

The following image represents Day 1 of experimenting:

The following image represents the status of our experiment on day 4:

There are many ways to preserve food or slow or stop the activity of the micro-organisms that make the fruit decay. Besides refrigeration, you can freeze, can, or pickle foods to protect them. We are observing how decay changes when we submerge the fruit with different elements.

As you can see from the photos and video, the air was the quickest way for the apple to decay, while vinegar prevented mold from growing on the apple. This is because vinegar has antimicrobial properties, which means that vinegar stops or kills microorganisms. The oil sample also didn’t decay as rapidly because certain oils contain elements that slow down the decaying process. Water showed an increase in mold because the microorganisms thrived in the moist environment and reproduced.

Printable Worksheet: Enhance Your Learning Experience

We’ve created a comprehensive printable worksheet to make the most of your Rotting Apple Experiment. This educational resource is designed to guide your child through the scientific process, from forming a hypothesis to drawing conclusions based on their observations.

The worksheet includes:

A hypothesis section where kids can predict what will happen to each apple slice
Daily observation logs for recording changes in each environment
Conclusion questions to encourage critical thinking about the experiment results
Bonus questions to expand learning beyond the experiment
A drawing section for visual learners to illustrate their favorite part of the experiment

This worksheet not only reinforces the scientific concepts explored in the experiment but also helps develop important skills such as:

Careful observation and data recording
Analyzing results and drawing conclusions
Comparing predictions with actual outcomes
Communicating scientific findings through writing and drawing

By using this worksheet alongside the experiment, you’re providing a well-rounded, hands-on learning experience that caters to different learning styles and reinforces key scientific principles.

Free Download

The rotting apple experiment worksheet, what to expect: observing decay in different environments.

As you and your children watch the apple slices over the next few days, you’ll notice fascinating changes:

Air : This slice will likely decay the fastest, as it’s exposed to all the microorganisms in the air.
Vinegar : You might be surprised to see little to no mold growth! Vinegar has antimicrobial properties that inhibit the growth of decay-causing organisms.
Water : This environment may promote mold growth, as microorganisms thrive in moist conditions.
Oil : The oil-submerged slice may decay more slowly, as certain oils have preservative properties.

The Science Behind Food Preservation

This experiment is a great way to introduce kids to food preservation. Discuss how different methods, such as refrigeration, freezing, canning, and pickling, all work to slow down or stop the activity of decay-causing microorganisms.

Video Tutorial: Watch the Rotting Apple Experiment in Action

Extended Activities: Taking the Experiment Further

Want to dive deeper into the world of decay and preservation? Try these extended activities:

Temperature Test : Set up the same experiment, but place one set in the refrigerator and one at room temperature. Compare the rates of decay.
Different Fruits : Repeat the experiment with various fruits or vegetables. Do some decay faster than others?
Microscope Exploration : If you have access to a microscope, examine samples from each container to see the microorganisms up close.
pH Testing : Test the pH of each environment before and after the experiment. How does pH relate to decay?

Benefits of the Rotting Apple Experiment

This simple yet effective experiment offers numerous benefits for young learners:

Hands-on Science : Kids learn best by doing, and this experiment provides a tangible way to observe scientific principles in action.
Critical Thinking : Encourage children to form hypotheses about which apple will decay fastest and why.
Observation Skills : Daily tracking of changes hones children’s ability to notice and record details.
Real-world Applications : Understanding decay and preservation has practical applications in daily life, from food storage to composting.
Introduction to Microbiology : This experiment offers a kid-friendly entry point into the fascinating world of microorganisms.

Great Books to Complement Your Experiment

Enhance your learning experience with these wonderful books about decay, microorganisms, and the scientific method:

“Tiny Creatures: The World of Microbes” by Nicola Davies
“A Mold is Born” by Julia Kuo
“Germs: Fact and Fiction, Friends and Foes” by Lesa Cline-Ransome
“The Magnificent Microworld” by Misha Maynerick Blaise
“11 Experiments That Failed” by Jenny Offill

Embracing the Messy Side of Science

The Rotting Apple Experiment might be a bit messy, but it’s an incredibly valuable learning experience. It teaches kids that science isn’t just about pristine lab coats and shiny equipment – sometimes, it’s about getting your hands dirty (figuratively, of course – always practice good hygiene!) and observing the natural world around us.

So, gather your materials, set up your experiment, and get ready to watch decay in action. Who knew that rotting apples could be so fascinating? Happy experimenting, young scientists!

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The Apple Mystery: A Fun Oxidation Experiment for Kids

Have you ever wondered why apples turn brown after you slice them? With this fun experiment, you can become a detective and crack the case!

Materials:

Sharp knife (with adult supervision)
Cutting board
5 small bowls or containers
Lemon juice
Salt water (mix 1 teaspoon of salt with 1 cup of water)
Baking soda water (mix 1 teaspoon of baking soda with 1 cup of water)
Pen and paper

Let’s Experiment!

Prepare your apple slices: Wash and dry the apple. Cut it in half and then into thin slices. Try to make the slices as even as possible.
Label your bowls: Write the names of each liquid on separate pieces of paper and attach them to the bowls. You should have bowls labeled “lemon juice,” “vinegar,” “salt water,” “baking soda water,” and “water” (this is your control group).
Dip and observe: Place one apple slice in each bowl. Make sure the slices are completely submerged in the liquids.
Wait and watch: Set a timer for 30 minutes and observe the apple slices. Do they all start to brown at the same rate? The scientific term for the browning process is oxidation. Are some liquids more effective at preventing browning than others?
Record your results: After 30 minutes, take out the apple slices and compare them. How brown are they? Write down your observations in a chart or table.
Analyze the results: Which liquid did the best job of preventing browning? Which liquid had the least effect? Can you explain why?

Explanation:

When the apple flesh is exposed to air, the enzymes in the apple react with oxygen in the air, causing the browning. Lemon juice, vinegar, and salt water are acidic, which slows down the enzyme activity/ oxidation. Baking soda water is alkaline, which can speed up the browning process.

Bonus challenge: Try the experiment with different types of apples and see if the results are the same. You can also try different liquids, like soda or honey water, to see how they affect browning.