Science project

Do Green Bags Really Work to Preserve Food?

Difficulty of Project



$ 20 -$30

Safety Issues

Safety glasses, apron and plastic gloves.

Material Availability

Readily available from local Home Depot.

Approximate Time Required to Complete the Project

4 weeks. This includes experimentation, collection, recording and analysis of data, summary of results and completion of bibliography.


To determine if Green Bags are the most effective at protecting and preserving fruits, vegetables and breads.

Materials and Equipment Required

  • 1 apple
  • 1 banana
  • 1 head of lettuce
  • 3 tomatoes
  • 3 slices of white bread
  • 3 slices of whole wheat bread
  • 10 green bags
  • 10 Hefty One Zip plastic bags
  • one sharp knife
  • one dozen Petri dishes with prepared and sterilized  beef broth agar ( purchased from Carolina Biological Inc. )
  • incubator (used at the school science lab)
  • surgical swabs
  • scotch or masking tape
  • a pair of scissors
  • paper towels for cleanup


On the informational level, this experiment serves to acquaint students with current data on food storage and food preservation. Students will take the opportunity to test out claims made by individuals who propose that their product (in this case, Green Bags) is superior when it comes to safely storing fruits and vegetables. In the process, students will become familiar with what occurs when foods are not properly sealed or refrigerated.

Research Terms

  • food preservation
  • dehydration
  • molds
  • fungi
  • bacteria
  • colonies
  • incubation
  • ethylene gas

Research Questions

  • What are the most common methods used to preserve food?
  • How do fungi and bacteria get into our food?
  • What is ethylene gas, where is it found and what does it do to our food?
  • How do we study the growth of fungi and bacteria?
  • How do bacteria harm us? How do bacteria help us?

Terms, Concepts and Questions to Start Background Research

  • What is a control? A control is the variable that is not changed in the experiment.
  • What purpose does a control serve? It is used to make comparisons as to what changed or possibly caused the change.
  • What are variables? Variables are factors that can be changed in an experiment.
  • What is an independent variable? The independent variable is the one that is changed in the experiment.
  • What is a dependent variable? The dependent variable is the one that changes as a result of the change in the independent variable.

Graphing Data

In each section of the experiment, use charts to display the obtained data.

Observations of Specimens

Note: Refrig =Refrigeration


Green Bag +


Hefty Bag +


Green Bags No Refrig

Hefty Bag No Refrig

Control Open Refrig

Controls Open No Refrig




Whole Wheat


Experimental Procedure

  1. State the problem you are going to investigate in this science fair project.
  2. Create and reproduce the data sheets you will use to record your observations.
  3. Gather all your materials.
  4. Put on your safety glasses, plastic gloves and apron.
  5. Gather all your materials.
  6. Cut the apple, banana, lettuce, and tomato, white and whole wheat breads into three equal segments.
  7. Place a piece of each into a green bag, a Hefty zip lock bag and on a large flat plate.
  8. Place one set of bags on the table next to the open flat plate of specimens and one set in the refrigerator. Keep them there for two weeks. At the close of the two weeks, make and record your observations in your chart.
  9. Take out your Petri dishes. Using a new surgical swab each time, swab each of the specimens and transfer the contents into separate Petri dishes. Close the dishes with scotch tape and label each one. Bring the Petri dishes to the school incubator.
  10. After three days, bring the Petri dishes home. Observe and record your observations. Photos of the Petri dishes make for an effective demonstration of your results. These should be accompanied by a descriptive statement.
  11. Analyze the total data and finalize your conclusion.
  12. Prepare your report and include all of the following: a clear statement of the problem, your hypothesis, and a list of the materials used. Include any safety precautions taken. Describe the procedures used. Include all the data that were gathered. Include all charts. Explain the purpose of the control. Formulate your conclusions. For dramatic value, you may include photos of the materials used or photos of you in the process of conducting this investigation. Include a bibliography of sources you used. You may wish to assess what you did and describe what you would do differently if you were to do this project again. You may also wish to expand this research the following year. What other materials might you investigate for this purpose?
  13. Note: If you wish to exhibit your Petri dishes containing the specimens grown, you may only do so with the permission of your teacher. The Petri dishes must remain sealed!


Grahame W. Gould, New Methods of Food Preservation.
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Warning is hereby given that not all Project Ideas are appropriate for all individuals or in all circumstances. Implementation of any Science Project Idea should be undertaken only in appropriate settings and with appropriate parental or other supervision. Reading and following the safety precautions of all materials used in a project is the sole responsibility of each individual. For further information, consult your state's handbook of Science Safety.

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