Astonishing Apples! What Preserves Apples Best?

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Author: Muriel Gerhard



Middle School

Difficulty of Project



$ 10 -$15

Safety Issues

Wear safety glasses, apron and plastic gloves.

Material Availability

Readily available from super market and from Chem. Scientific.

Approximate Time Required to Complete the Project

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


To determine which of the following substances best preserves an apple: lemon juice, lemon juice plus ice, citric acid, sugar syrup, pure ascorbic acid?

Materials and Equipment required

3lbs of apples, lemon juice, citric acid, salt, sugar syrup, pure ascorbic acid powder, water, paring knife, zip-lock freezer bags, stirrers, 4 bowls, and 7 pint sized containers.


On the information level, this experiment serves to acquaint students with current data on the chemistry of preserving light colored fruit such as apples, pears and peaches. Students learn that enzymes in these fruits cause this oxidative browning when these fruits are peeled or cut. In addition they learn that the browning can cause loss of vitamin C. To prevent this browning and this enzyme interaction, a variety of substances are used with differing results. What the student comes away with is an understanding of some of the ways we use the science of chemistry to preserve and thereby protect our food supply.

This science fair experiment also serves to acquaint students with the essential processes of sciencing such as the importance of the use of a control, of identifying dependent and independent variables, of data collection, of pictorial and or graphic presentation of data and of being able to make better judgments as to the validity and reliability of their findings. They take on the role of scientists and in the process they learn to act as one.

Research Terms

  • enzymes
  • browning
  • oxidation
  • preservation
  • vitamin c
  • ascorbic acid

Research Questions:

  • Whatcauses the browning of apples and pears when they are peeled and cut?
  • How do enzymes affect oxidation?
  • What are some of the methods used to preserve these fruits?

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.

Charting and or Graphing Data

Lemon Juice


Lemon Juice plus Ice


Citric Acid


Sugar Syrup


Ascorbic Acid





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