Food Preservation Experiments

Instructor: Amanda Robb

Amanda holds a Masters in Science from Tufts Medical School in Cellular and Molecular Physiology. She has taught high school Biology and Physics for 8 years.

In this science fair experiment, we'll be testing the efficacy of various methods of food preservation. Try this lesson if you want to learn about how to keep your own food fresh and reduce food waste.


Research Question: Which type of container best preserves food?
Age: Middle school and up
Safety Concerns: None
Time: About 10 days
Independent variable: Type of container
Dependent variable: Days until spoiling
Controlled variables: Amount of food used, temperature and ambient conditions

It's breakfast time and you're ready to start the day right with a healthy bowl of oatmeal, milk and strawberries. But, when you take out the container of strawberries, you find them covered with a thick fur. We've all been there. Bacteria and mold lie in wait on counter surfaces, in our air and even in the refrigerator to colonize our food and reproduce. If you're interested in the different types of mold before we get started, take a look at this lesson: What is Mold? - Definition, Types & Causes.

Growth of mold and bacteria cause food to spoil
moldy strawberries

Although this might be a mild inconvenience to you, food waste, or food that is thrown away and left uneaten, is a serious problem in America. As of 2010, the United States Department of Agriculture (USDA) estimates that 30 - 40% of our food supply is lost as food waste, or about 161 billion dollars in food. Although not all food waste is created in our homes, spoiled food is certainly part of the problem.

Household food waste is a big problem in America
household food waste

Today, you'll be testing three different methods of food preservation, which prevent food from spoiling, to find the best way to keep our food fresh and reduce food waste. Although we suggest specific methods here, you can experiment with different methods of preservation that you frequently use. We will also test strawberries, but you can change this to test whatever foods you like.


  • Three different food containers (such as a plastic zipper bag, tupperware, and one 5'' square piece of plastic wrap)
  • One food scale
  • Three medium strawberries weighing about 20 grams
  • Camera to photograph progress (optional)
  • Notebook to record observations and create graph
  • Data table:

Type of Container Total Days to Spoil
Plastic zipper bag
Plastic wrap


1. First, weigh your strawberries, making sure each weighs the same amount.

2. Next, place one strawberry in the plastic zipper bag, one strawberry in the tupperware, and one in a 5'' square piece of plastic wrap.

3. Seal each of the containers.

4. You might want to take a picture of the original condition of the strawberries. Qualitative data can also be useful in your analysis.

5. Now it's time to wait. Let your containers sit in the same temperature with the same amount of light, such as on a counter, overnight.

6. The next day, photograph your strawberries again and record any observations in your notebook.

7. Repeat steps 5 - 6 until all the strawberries are spoiled. When a strawberry spoils, record the number of days it took to spoil in your data table.

8. When all strawberries are spoiled, create a graph comparing the type of container to the number of days it took to spoil to analyze your results.


If your strawberries aren't getting moldy, wait a little bit longer. If you have ever abandoned leftovers in the fridge, you know food will eventually spoil.

Discussion Questions

Which container preserved the strawberries best?

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