Does Controlled
Atmosphere Storage Affect the
Malic Acid and Starch Levels in Apples? |
Researched by Alyssa B.
2002-03 |
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PURPOSE
The purpose of this experiment was to determine if controlled atmosphere
apple storage would affect the amount of malic acid and starch levels in
apples.
I became interested in this idea when one day I bit into an apple and
it was crisp, mild, smooth and tart, while a week later the same batch
was grainy and had a not-so-good taste.
The information gained from this experiment may be useful for consumers
and people in the apple industries.
HYPOTHESIS
My 1st hypothesis was that the malic acid content would decrease as
the storage temperature increased.
I based my 1st hypothesis on the fact that apples ripen faster in warmer
temperatures and malic acid content decreases after ripening.
My 2nd hypothesis was that the starch content would decrease as the
storage temperature increased.
I based my 2nd hypothesis on a quote from a fruit storage article that
said controlled temperature storage slowed the ripening process.
My 3rd hypothesis was that the longer the apples were stored the greater
the malic acid content.
I based my 3rd hypothesis on the quote The malic acid is pure in the
apple just before it is ripe, but is less afterwards.
My 4th hypothesis was that the longer the apples were stored the greater
the affect on the starch content.
I based my 4th hypothesis on storage articles about temperature and
its affect on ripening and sugar/starch content.
EXPERIMENT DESIGN
The constants in this study were:
§ Number of apples juiced
§ Amount of juice used for each test
§ Amount of water used for each test
§ Temperature of the 4º C room
§ Temperature of the 21º C room
§ Temperature of the 32º C room
§ Type of apple and harvest week
§ Number of apples used for starch test
§ Type of automatic titrater
The manipulated variables were the temperature the apples were stored
at and the amount of time they were stored.
The responding variable was the amount of malic acid and starch in
apples.
To measure the responding variable I used a titrater to measure the
amount of malic acid and an iodine solution to measure the starch.
MATERIALS
QUANTITY ITEM DESCRIPTION
36
Red delicious apples
3
30x46x13cm cardboard box
1
clean paring knife
1
15x46x5cm cardboard box
1
5ml. Pipetteman pipette
13
sml.pipette tips
1
250mL. Beaker
3
400mL. pipette
1
Omega Fruit & Vegetable Juicer
100mL.
Iodine spray (0.5% I2)
1
0.4732 Spray bottle
1
clean plastic cutting board
1
Schotts automatic titrater
1
stir bar
1
safety glasses
1
fume hood
1
100mL. Graduated cylinder
1300mL.
Distilled water
1
4º C storage room
1
21º C storage room
1
32º C storage room
1
Adult supervisor
PROCEDURES
Time Zero
1. Set 3 apples aside for later use.
2. Put 12 apples in each of 3 smaller boxes.
3. Label one A, one B, and one C.
4. Put box A in 4º C storage room.
5. Put box B in the 21º C storage room.
6. Put box C in the 32º C storage room.
7. Cut the three apples you set aside in half horizontally.
8. Put the bottom half in the shallow cardboard box and place under
fume hood. Label box in thirds A, B, and C.
9. Spray the tops of the bottom half with iodine solution.
10. Cut the top half in 1/8s.
11. Put a beaker under spout of the juicer and push two pieces of apple
into juicer.
12. Discard juice made from the pieces and put the beaker labeled A
under the spout.
13. Push one piece of apple into the juicer at a time until all pieces
are juiced. Empty contents inside juicer (pulp) into garbage can.
14. Take juice and using the pipette, put 10 mL of juice into a beaker
and add 100 mL of distilled water.
15. Put stir bar in and put under electrode of the titrator.
Insert sodium hydroxide ejector; turn the titrator and the stir bar on
according to the supervisor.
16. Record malic acid and starch levels.
17. Clean juicer and supplies.
Procedures
1. Collect three apples from each room in buckets labeled A, B, and
C.
2. Cut all the apples in the A bucket in half horizontally on the plastic
cutting boards.
3. Put the bottom half in the shallow cardboard box and place under
fume hood.
4. Spray the tops of the bottom half with iodine solution.
5. Cut the top half in 1/8s.
6. Put a beaker under spout of the juicer and push two pieces of apple
into juicer.
7. Discard juice made from the pieces and put the beaker labeled A
under the spout.
8. Push one piece of apple into the juicer at a time until all pieces
are juiced. Empty contents inside juicer (pulp) into garbage can.
9. Set aside for later use.
10. Repeat steps 2-10 for apple buckets B and C.
11. Take juice and using the pipette, put 10 mL of juice into a beaker
and add 100 mL of distilled water.
12. Put stir bar in and put under electrode of the titrator.
Insert sodium hydroxide ejector; turn the titrator and the stir bar on
according to the supervisor.
13. Record malic acid and starch levels.
14. Clean juicer and supplies.
RESULTS
The original purpose of this experiment was to determine if controlled
atmosphere apple storage affects the amount of malic acid and starch in
apples.
The results of the experiment were that the malic acid content decreased
as the storage temperature increased and that the starch content decreased
as the storage temperature increased. The malic acid and starch content
both decreased over time in storage.
See my table and graph.
CONCLUSION
My 1st hypothesis was that the malic acid content would decrease as
the storage
temperature increased.
My 2nd hypothesis was that the starch content would decrease as the
storage temperature increased.
My 3rd hypothesis was that the longer the apples were stored the greater
the affect on the malic acid content.
My 4th hypothesis was that the longer the apples were stored the greater
the affect on the starch content.
The results indicate that all hypothesizes should be accepted.
Because of the results of this experiment, I wonder if the apple the
apple dehydrates in warmer climate and makes a higher concentration of
sugar and malic acid.
If I were to conduct this project again I would have had more apples
to test. I also would have more frequent tests like every two days instead
of once a week, also I would have replicated my entire experiment.
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RESEARCH REPORT
Apples
History of Apples
The apple or Malus sylevestris dates back to 6500 BC. It is not native
to the United States but is native to southwest Asia. Julius Caesar planted
the very first apple tree in England and the English brought seeds to the
New World. The Massachusetts Bay Company planted the first tree.
The apple is made-up of 85% water, vitamin A and C, potassium, pectin,
and fiber. There is also malic acid in apples. The malic acid is what gives
the apple its aroma, taste, and also healthfulness. There is also a lot
of starch in an apple that is crunchy but is little in an apple that is
mushy and grainy.
The Apple Tree
The apple tree is twenty to thirty feet tall when it is fully-grown.
It belongs to the rose family because of its blossoms that eventually turn
into apples. The tree has to mature for four years before it bears fruit,
and bears fruit for forty years. The tree has head-spreading branches,
which means the branches spread apart near the top of the tree. The trees
grow when bees pollinate the stigma of the blossom. The small green cup
that holds the blossom is called a calyx. The apple wood is used for engravings,
carvings, saw handles, and ax handles.
Crops
Worldwide, we growers produce 2 billion bushels of apples a year.
China produces 630 million bushels of apples annually the most in the world.
The harvest time is late summer to fall depending on the variety. A fourth
of the apples the world produces goes into cold storage. The United States
ranks 2nd, with 260 bushels, of apples produced. Washington produces the
most apples in the United States. France was third on this list.
Health
Apples are very good for you. There are condensed tannins found in the
juice of apples that help prevent plaque on the teeth. Apples also prevent
periodontal or gum disease. Apples also have anti-adhesion properties.
You can eat apples fresh to relieve constipation and diarrhea. An apple
prevents urinary tract infection and reduces the risk of heart disease.
Malic Acid
Malic acid is an important ingredient in apples, therefore it is also
known as apple acid. Malic acid is a colorless crystalline compound that
is a metabolite in the Krebs Cycle that produces 90% of the energy within
its cells. Malic acid binds to aluminum. It removes the aluminum from the
enzyme tubulin-which protects and maintains nerves-then is removed from
the body through urine. There is roughly 0.2-1.0 gram of malic acid in
an average apple (the part that you can eat). Malic acid is what makes
the saying An apple a day keeps the doctor away true!
Health
You cannot become deficient in malic acid because the body produces
malic acid itself. Malic acid also helps prevent many diseases and conditions.
Fibromyalgia is a disease that is in the muscles and malic acid is a very
popular remedy to decrease pain related to it. Malic acid also is a remedy
for hypoxia-related conditions which is respiratory or circulatory insufficiency,
or when you dont get enough oxygen. Some scientists believe that malic
acid can also reduce the risk of Alzheimers disease. Malic acid also helps
the body make ATP more efficiently. ATP is the energy currency that runs
the body, from food.
Starch
Starch is a biopolymer system including mainly Amylose and Amylopectin.
Starch is used for pressing clothes and making foam packing (because it
is biodegradable). Starch is made up of glucose, or other sugar, in repeated
units, which your body can burn for energy. A way to test for starch is
to use an iodine solution on the object and it will turn a blue-black color
if it has starch in it. This happens because the starch chemically reacts
to the iodine solution.
Heath
One third of the total weight of food intake is starch. You can find
starch in many different foods including potatoes, grains like corn and
wheat, and apples. Red Delicious apples should have a 1.5 - 2.0 rating
on the starch scale to be perfect. You get most of the energy you use from
starch.
Controlled Atmosphere
Controlled atmosphere is a non-chemical storage process that uses an
airtight room. The oxygen is reduced in the room, by adding nitrogen. The
oxygen drops from about 21% in the regular air that we breathe to one or
two percent. The temperature in the room is kept at32 to 36 degrees Fahrenheit.
The humidity in the room is kept at about 95%. The carbon dioxide level
is also controlled. They change the conditions of the rooms depending upon
the variety of the apple. Machines and computers help keep the conditions
stable and constant.
History
Controlled atmosphere started in England before World War _ when some
farmers discovered that there produce lasted longer if it was stored in
an airtight room. The scientists had to figure out why they lasted longer.
Researches in Washington have been among the leaders in controlled atmospheres.
Controlled Atmosphere started in the United States in 1960, Washington
now has the most controlled atmosphere storage of any growing region.
How it Works
Apples breathe just like humans, in with oxygen and out with carbon
dioxide, as the starch turns to sugar. In the airtight rooms, the oxygen
turns into carbon dioxide, which slows the ripening process.
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| BIBLIOGRAPHY
Malic Acid Malic Acid 11/21/02 http://www.hollandandbarrettt.com/Supp/Malic_Acid.htm
Morphologic Change of Starch Granules in the Apple cv. Mutsu
During Ripening and Storage Scanning 11/21/02
http://www.scanning-fams.org/scanabstracts/SCANNING99/21326
Washington State Apple Commission. Controlled Atmosphere Storage (CA)
Core Facts 1/30/03 http://www.bestapples.com/facts/controlled.html
Washington State Apple Commission. Keep Your Family Healthy Health
& Nutrition 10/10/02 http://www.bestapples.com/healthy/index.html
What is Starch What is Starch 1/29/03
http://www.poco.phy.cam.ac.uk/research/starch/whatis.htm
Washington Apple Maturity Program Handbook.1986.Washington Apple Maturity
Program,Wenatchee,WA.
Washington State University,Tree Fruit Research and Extension Center.
Postharvest Information Network 1/29/03 http://postharvest.tfrec.wsu.edu/index.html
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ACKNOWLEDGEMENTS
I would like to thank my Supervisor from TreeTop for helping me learn
to use all the materials. I would also like to my advanced science teacher
for guiding me through the project and making sure I did all the steps
required of me.
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