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.
How to preserve apples
This simple science activity investigates ways to stop apples from spoiling without a fridge!
What you need for an apple rotting experiment
- One apple
- 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 – you 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 )
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!
Make your own rock candy!
Or, go all out and have a Science Bake OFF!!
You can find lots more GROSS Science experiments in my new book too!
Last Updated on March 20, 2023 by Emma Vanstone