The Effectiveness of Various Preservatives on the Color of Applesauce

Photo of Kacey at Mid Columbia Science Fair

Researched by Kacey H.
2005-06



PURPOSE

The purpose of this experiment was to compare the effectiveness of various preservatives on the color of applesauce.

I became interested in this idea because I like apples and applesauce. Nearly all my friends like applesauce and so do my family members. I have noticed that infants are often fed applesauce as one of their first solid foods. I have also noticed that people who are sick in the hospital often are given applesauce with their meal. I also know that elderly people in nursing homes also seem to eat applesauce fairly often. Applesauce seems to be an important part of people’s diet.

The information gained from this experiment could help nutritionists and apple processors learn about the effectiveness of various preservatives on the color of applesauce. This would also help those who eat applesauce as part of their diet.


HYPOTHESIS


My hypothesis was that, the applesauce treated with the ascorbic acid and heat would get the highest USDA score.

I based my hypothesis on finding out that ascorbic acid works very well when making applesauce. I thought heat would even make it lighter.


EXPERIMENT DESIGN

The constant in this study was: 
•    The raw applesauce prior to treatment
•    The type of apples
•    Amount of apples
•    Grinding method
•    General testing procedures
•    Use of colorimeter

The manipulated variable was the type of preservative used to make applesauce.

The responding variable was the color (lightness) of the applesauce.

To measure the responding variable, I used a Hunter Reflectance Spectrophotometer (colorimeter.)


MATERIALS


QUANTITY		 ITEM DESCRIPTION
8
 Apples
1 g.
 Citric Acid
3g.
 Ascorbic Acid
1
 Microwave Oven
1
 Food Processor
1
 Apple Peeler
1
 Hunter Reflectance Spectrophotometer
1
 Knife
1
 Cutting Board

   
   
    
      
 
PROCEDURES

1.    Set up materials at local apple processing lab.
      A.)    Peel and core 2 apples (I used “Cameo” apples)
      B.)    Use the peeling and coring machine.
      C.)    Finish peeling off the extra skin by hand with peeling knife
2.    Treatment #1 (Ascorbic acid preservative plus heat)
      A.)    Cut up two apples previously peeled and cored into 8 pieces each.
      B.)    Weigh and record.
      C.)    Place them all into food processor.
      D.)    Add 0.3 grams of ascorbic acid to the apples in food processor.
      E.)    Grind up the contents for 30 seconds, then stop.
      F.)    Stir well.
      G.)    Grind for another 30 seconds.
      H.)    Pour all ground up contents into a cup.
      I.)    Heat the applesauce (which you just made) slowly in microwave oven until it is 88° C. (190° F.)
      J.)    Test applesauce with the colorimeter
      K.)    Record results on the data table (shown in the appendix)
3.    Treatment #2 (Citric acid preservative)
      A.)    Repeat Steps 1 and 2, except do NOT heat or add ascorbic acid.
      B.)    Instead, add 0.3 grams of Citric acid
4.    Control Group (Applesauce with no preservative)
      A.)    Repeat Steps 1 and 2, except do NOT add ascorbic acid (and do not heat)
5.    Treatment # 3 (Ascorbic acid preservative)
      A.)    Repeat Steps 1 and 2, except do NOT heat, and ADD ascorbic acid!
6.    Test each applesauce every 15 minutes, four times in the colorimeter.


RESULTS

The original purpose of this experiment was to compare the effectiveness of various preservatives on the color of applesauce.

The results of the experiment was the Ascorbic acid plus heat preservative, had the highest and best USDA score. 

See the table and graph below.


CONCLUSION

My original hypothesis was the applesauce treated with the ascorbic and heat would get the highest USDA score.

The results indicate that this hypothesis should be accepted, because after testing the applesauce, the ascorbic acid + heat treatment resulted in the highest USDA score.

After thinking about the results of this experiment, I wonder if we ground up the apples with a different method, would the colorimeter data still be relatively the same?  I also wonder if other types of apples, like Granny Smith, would have similar results.

If I were to conduct this project again I would grind up the apples more carefully.  In this experiment, I got better and better at grinding up the apples every time.  This affected the colorimeter results; but not greatly.  Lastly, I would do more trials for each treatment.  In this experiment, I only did one trial for each of the four preservatives, but I tested the one applesauce treatment four times.  I should have used the system above, but repeated two or three times.
 
RESEARCH REPORT

Introduction
The apple is one of the most important and popular fruits.  Much of the yearly apple crop must be processed, then canned, frozen, or dried for year-round use.  Several methods and chemicals are used to help preserve the quality of canned applesauce so it has an appealing color and flavor as well as good nutrition.

Apples
There are hundreds of different varieties of apples. The colors range from different shades of red, to green, to yellow. Their flavor is from tart to sweet. Apples are part of the rose family. Their white flowers open in the spring, and look like small roses. The apple is a pome.  It is a fruit that has a fleshy outer layer and a paper-like core.  The core surrounds or encloses the seeds.  There are usually 5 to 10 seeds per apple.

China leads the world in apple production, followed by the U.S.  Other leaders are Italy and Turkey. In the United States, apple growing is very important economically, especially in the Pacific Northwest. Washington produces more apples than any other state. The nation’s apple crop totals about 5 million tons each year. That generates about $1.75 billion.

Three common varieties of apples are Delicious, Golden-delicious, and Granny Smith. They make up two-thirds of the apples produced in the U.S. There are 25 wild kinds of apples. Eight of these are grown in the United States. Most of them are crab apples.

Over half of the apples grown commercially, are eaten fresh. Apples can be used in pies, salads, and other dishes. They are used in making applesauce, apple juice, apple butter, jelly, and wine. Apple juice can be made into vinegar. Most of these products can be canned or bottled. Some can be dried or frozen. Since apples are about 85% water, they dry well. They are nutritious, providing vitamins A and C, potassium, pectin, and fiber.

Apple trees can grow more than 40 feet (12 meters) tall.  Most apple trees don’t grow well in areas with extremely cold winters or long, hot summers, but they thrive in regions with moderately cold winters.  The fruit does not grow during the winter.  This is when the trees have time to regenerate.

Most apple trees are grown from buds.  The buds are cut from a healthy tree that has produced the kind of fruit needed.  Apple trees in orchards are planted in rows from 10 to 30 feet (3 to 9 meters) apart.  This spacing makes it so that the growers can spray and pick the fruit easily.  A young apple tree starts to bear fruit in 3 to 5 years.  Apple trees can grow fruit for as long as 100 years, but most apple trees in orchards, are replaced every 12 to 20 years.

In late spring, apple trees bloom, and grow little white flowers that look like roses.  However, the flowers must be pollinated by insects.  For this reason, some growers will place bee hives in the trees while they blossom.  Seeds grow in the ovary of a pollinated flower, while the ovary and the other parts of the flower develop into the fruit.  Most kinds of apples ripen in 140 to 170 days after pollination. Apple growers start to harvest their crop in late summer or early fall.  The harvest dates vary according to the kinds of apples.  Apples are picked by hand.

Why Cut Apples Turn Brown
Fresh cut apples turn brown when iron-containing chemicals that are inside apple cells react with oxygen in the air.  This is called oxidation.  We see this every day when scabs on cuts turn brown, or when iron objects rust.  

There are millions and millions of tiny cells in an apple.  One way that the apple gets exposed to oxygen is when it’s cut open.  This damages thousands of protective cell walls and exposes their contents to oxygen in the air.  Then the oxidation of cell contents begins.  Bruised apples also encounter oxidation.  When an apple gets dropped or damaged in some way, many of the cell walls become broken. The contents of the cells then flow freely inside the apple, where they react with the air that is inside the apple.  Apples are 80% air, that’s why they float.

Food Preservation
One of the bad things about canning food is that the heat needed for sterilization changes the food’s texture, color, and flavor. Also, some of the nutrients, like vitamin C are lost during this canning process. However, canned foods are popular with people because of their low cost, variety, and the usually long shelf-life.  Various chemical preservative are used to improve the quality of canned, frozen, or dried foods.  These include citric acid and ascorbic acid.

Acids
An acid is a group of compounds with certain similar properties. An acid can be defined as a compound that dissolves to produce hydrogen ions (H+) in solution.  A hydrogen atom has one proton, which has a positive electric charge, and one electron, which has a negative charge. When a hydrogen atom is changed into an ion, it loses its electron and becomes positive.  The solutions of acid have a sour taste and a prickly or burning feel if they come in contact with the skin.  They dissolve many metals.  Many acids are poisonous and strong acids can also cause severe burns.  Chemical compounds called bases or alkalis neutralize acids.  

Some acids form naturally, and some are needed for life.  For example, hydrochloric acid (HCl) is made in the human stomach and helps digestion.   Acids are also used widely in industry.  Some are also used in a large number of foods and beverages.  Some are used as preservatives.

Citric Acid    
Citric acid is a common organic acid that gives lemons, limes, and other citrus fruits their sour taste. Citric acid is used as a flavoring for soft drinks and medicines.  The industry uses it in chemicals, alkyd resins, plasticizers, inks, and as a mordant  (dye-fixative.)  It is also used to preserve color and flavor in canned and frozen fruits and fish. Citric acid is prepared commercially from fermentation of sugar, and by extraction of lemon juice, lime juice, and pineapple residues.  Pure citric acid forms colorless, odorless crystals that have a good, sour taste.  It melts at 153° C.  Citric acid can combine with metals to form salts called citrates

Enzyme
An enzyme is a molecule that speeds up the chemical reactions in living things. Without enzymes, the reactions would be too slow or would not occur at all. Life would not be possible, if there were no enzymes. The human body has thousands of kinds of enzymes. They all have specific jobs. Without them, you couldn’t breathe, see, move, or digest food! Photosynthesis in plants also needs enzymes to occur.  All living cells make enzymes, but enzymes themselves are not alive. Most enzymes are proteins.  They function by altering other molecules. They combine with them to make a complex molecular structure. This is the point at which the chemical reactions take place. One enzyme can perform this whole function one million times a minute.

Summary
Overall, the apple is one of the most important and popular fruits.  Much of the yearly apple crop must be processed, then canned, frozen, or dried for year-round use.  Several methods and chemicals are used to help preserve the quality of canned applesauce so it has an appealing color and flavor as well as good nutrition.

BIBLIOGRAPHY

 “Acid.” World Book Multimedia Encyclopedia. 2003.

“Apples.” World Book Multimedia Encyclopedia. 2003.
 
 Baranoswki, John.  Personal interviews.  January, 6, 2006 and January, 13, 2006

“Citric Acid.”  World Book Multimedia Encyclopedia. 2003.

“Enzyme.” World Book Multimedia Encyclopedia. 2003.

“Food Preservation.” World Book Multimedia Encyclopedia. 2003.

 “Oxidation.”  World Book Multimedia Encyclopedia. 2003.
 
“Raising Apples.” World Book Multimedia Encyclopedia. 2003.
 
“Varieties of Apples.”  World Book Multimedia Encyclopedia. 2003.

“Why Fresh Cut Apples Turn Brown.” http://geocities.com/perfectapple/brown.html


ACKNOWLEDGEMENTS

I would like to thank the following people for helping make my project possible:

•    My parents for helping me on my project at home and helping get to the laboratory were I conducted my experiment.

•    Cierra, for helping me when I was down and thought that my project was going to fall apart, (which it did)

•    Mr. Newkirk, for being my kind, helping, encouraging teacher.  Mostly, when I had to re-start my science project.

•    John Baranowski and Tree Top for being my “Mentor” and letting me use the lab at Tree Top.

•    Mrs. Veirnes for being my “second” teacher when Mr. Newkirk was un-available. 

Top of page

Menu of 2005-2006 Science Projects

Back to the Selah Homepage