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PURPOSE
In phase I of this experiment the purpose was to determine how the maturity
of apples affected the starch and malic acid content.
In phase II the purpose was to determine the level of maturity in different
apple varieties using Granny Smith, Golden Delicious and Red Delicious.
I became interested in this idea because my mother works at Tree Top
and I know that the information gathered from this experiment can prove
useful to some people in the juice industry.
The information gained from this experiment will help smaller companies
in juice manufacturing who do not have the resources to conduct research.
Because these are low cost ways to find out valuable information.
HYPOTHESIS
In phase I my hypothesis was that Granny Smith apples would have more
malic acid content than golden delicious or red delicious.
I based this hypothesis on an article I read in the Pennsylvania Apple
Production Guide that said that Granny Smith apples have a sour starchy
taste.
My second hypothesis for both phases was that storage time would increase
the apples maturity: lower malic acid and starch levels, and higher brix
levels.
I based this hypothesis on the principle that starch is converted into
simple sugars as the apples mature.
My hypothesis for phase II was that Red delicious apples would have
the lowest malic acid content.
I based this hypothesis again on the Pennsylvania Apple Production Guide
and an advertisement for the dietary supplement malic acid that stated
that malic acid had a sweet taste and Red Delicious has the sweetest taste
of these three types of apples.
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EXPERIMENT DESIGN
The constants in this study were:
Phase I only
1. Amount of iodine sprayed
2. Spray bottle
3. Amount of light in the room
Phase I and II
1. Room
2. Temperature
3. No wind or fans
4. Apples cut in the same spot
5. Same amount of apples at one time
6. Frequency of testing, every 7 days
7. Knife
8. Number of apples for each variety
Phase II only
I. Use the same titrator or pH meter
II. Use the same refractometer
The manipulated variable was the type of apples
The responding variable was the maturity of the apple
To measure the responding variable I used a titrator to measure the
malic acid level and iodine to measure the starch level
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MATERIALS
| QUANTITY |
ITEM DESCRIPTION |
| 100 ml. |
0. 1Normal Iodine solution |
| 1 |
100 ml spray bottle |
| 21 |
Granny Smith apples |
| 21 |
Golden Delicous |
| 21 |
Red Delicous |
| 1 |
titratior; ph meter |
| 1 |
clean paring knife |
| 1 |
plastic cutting board |
| 1 |
safty glasses |
| 1 |
pair of gloves |
| 1 |
25ml reuseable |
| 1 |
fruit jucier |
| 5 |
Cardboard Boxes |
| 1 |
Adult Superevisor |
| 3 |
plastic cup |
| 15 |
straws |
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PROCEDURES
I. Mix 0. 1N Iodine solution
1. Buy 0. 1Normal iodine.
2. Careful transfer the 0. 1N iodine into the spray bottle.
3. Store the iodine in an amber bottle to prevent exposure to the light.
4. If the spray bottle is not in an amber container, completely cover
the spray bottle with aluminum foil.
II. Get the apples ready
1. Wash the apples using cold clean water.
2. Dry the apples before cutting them.
3. Cut the apples horizontally down the middle you are going to use
(which should only be three of each type of apple)
III. Prepare the test
A. Check your variables
1) Laboratory room temperature, amount of air movement and light
2) Use three apples of each variety, harvested at same time
3) All apples stored at the same condition, room temperature.
4) Apples cut horizontally across the middle
B. Put on safety gear: safety glasses, protective gloves, plastic apron
C. Label each type of apple with colored stickers
1) Granny Smith - Green sticker
2) Golden Delicious - Yellow sticker
3) Red Delicious - Pink sticker
D. Count your materials
E. Separate your materials from the things you are going to use in
Phase 1 and in Phase 2.
F. Prepare your materials
IV. CONDUCTING THE TESTING FOR STARCH
1) Cut the apples using a knife on the cutting board.
2) Put each variety and group them on a cardboard box.
3) Put the labels at the bottom of each group to identify the variety.
4) Spray each apple half with 0. 1 N Iodine until the top portion of
each apple is fully covered with iodine.
5) Let it sit for 2 hours until the iodine is fully absorbed.
6) Compare the appearance of the apples with the pictures being used
as the standard.
7) Enter the number on the worksheet indicating the starch level.
8) Take the picture of the apples.
9) Discard apples
10) Repeat steps II-IV every 7 days.
V. TESTING FOR MALIC ACID
1) Juice the apples
a) Put each variety of apples in the blender
b) Recover the juice from the mashed apples using the strainer.
2) Measure 25 ml of the sample using a volumetric pipette
3) Transfer the sample into the beaker.
4) Add deionized water up to 35 ml mark on the titration beaker.
5) Properly secure the beaker to the titration head with glass membrane
and contact point of the reference electrode properly immersed.
6) Enter method number from the titrator, test for malic acid at 8. 2
pH endpoint.
7) Press Method key. Press Run key
8) Enter 25 as sample size. Press Run key
9) Enter sample identification. Press Run key twice more
10) Rinse after each titration
11) Enter the result into your worksheet.
VI. Testing Brix
1) Put the excess juice from the malic acid test from each type of
apple in a small plastic cup
2) With an eyedropper put two drops of juice to cover the lens.
3) Then pull down the lid
4) Record data
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RESULTS
In phase I of this experiment the original purpose was to determine
how the maturity of apples affected the starch, malic acid, and brix content.
In phase II the original purpose was to determine the different levels
of maturity in different apple varieties using Granny Smith, Golden Delicious
and Red Delicious.
The results of this experiment were that Golden Delicious apples
and Granny Smith apples had the highest starch at 5. 5 and Red Delicious
apples had the lowest level of starch at 6. Red Delicious had the highest
levels of brix with 14. 94% and second highest brix level was Golden delicious
with 14. 39%, and the apple with the lowest brix level was Granny Smith
apples with 12. 25%. Granny smith had the highest amount of malic acid at
0. 56%, Golden Delicious had 0. 30%, and the lowest malic acid level was
Red Delicious at 0. 21%
See My Data Tables and Graphs
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CONCLUSION
In phase I my hypothesis was that Granny Smith apples would have more
malic acid content than golden delicious or red delicious.
The results indicate this hypothesis should be accepted, because the
results showed that granny smith apples had 0. 56% of malic acid, red Delicious
apples had the result of 0. 21% of malic acid and Golden Delicious had the
result of 0. 30% of malic acid.
My second hypothesis for both phases was that storage time would increase
the apples maturity: lower malic acid and starch levels, and higher brix
levels.
The results indicate this hypothesis should be accepted.
My hypothesis for phase II was that Red delicious apples would have
the lowest malic acid content.
The results indicate this hypothesis should be rejected, because golden
delicious had the result of 0. 30% of malic acid and red delicious had the
result of 0. 21% of malic acid.
Because of the results of this experiment, I wonder if cold storage
would affect the maturity changes.
If I were to conduct this project again I would have used a fruit juicer
to juice the apples. I would also test more apples each week. I would conduct
it over a time of 10 weeks. I would get a more precise starch comparison
guide. Finally, I would test more types of apples.
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Research Report
Introduction
Apples contain starch and sugars that provide energy and help maintain
your blood sugar. Apples also contain malic acid, which can reduce the
risks of many diseases. When you mix all of these nutrient values you get
one of the healthiest fruits.
Apples
Apples are one of the most important fruits, and one of the most popular
ones too. Since prehistoric times people have eaten apples and also learned
how grow them in many different environments.
There are hundreds of types of apples. Their color ranges from various
shades of red to green to yellow, and their flavor ranges from sour to
sweet.
Apple farmers grow about 2 billion bushels of apples yearly. China is
the top producer of apples closely followed by the United States, France,
Italy, and Turkey. In the U. S. apple growing is a very important industry
in many regions, especially in the Pacific Northwest. Washington grows
more apples than any other state in the U. S. The United States grows about
260 million bushels a year bringing in more than 1. 5 billion dollars.
Apples are pomes. A pome is a fruit that has an outer layer like a skin,
several seeds but not stones or pits, and a fragile core. An apple usually
has 5- 10 seeds enclosed in the core. Another example of a pome is a pear.
Apples are not only pomes they are also hybrids. A hybrid is a cross of
plants of the same species. Two different types of that plant mixed make
a hybrid.
Apple Trees
Apple trees belong to the rose family. Their white blossoms look like
tiny roses. Most apple trees grow about 30 feet tall. The trunk
is rather short and stocky. The head or top of the tree is round with an
assortment of delicate twigs along side the branches. The bark is gray
(not brown) and flaky. Apple leaves are pale green, oval shaped and have
saw tooth edges. They range from one to four inches long. Their undersides
are fuzzy and their topsides are smooth. The leaves do not oppose each
other, they alternate. The apple tree is strong and sturdy. The branches
are heavy and twisted. Even the small limbs are rather husky. They have
to be; a crop of apples is heavy and could easily snap a delicate tree.
Sometimes you might see a wild apple tree. Most wild apples are extremely
sour and hard. But these apples will not go to waste, deer often eat them.
Apples vs. Health
Apples are very healthy for you. There are a large amount of tannins
found in apple juice that prevent discoloration and plaque build up. Apple
juice also prevents gum diseases such as gingivitis. Apples also have anti-body
properties. To cure diarrhea and constipation you can eat fresh apples.
Apples also help prevent heart disease and urinary tract infections.
How Apples Grow
When an apple tree blooms, the blossoms grow in clusters at the end
of the twigs. A ring of pale, soft leaves surround each cluster. Both the
flowers and the leaves come from buds produced the season before and protected
over the winter by fuzzy scales. As the flower buds, open, they leave a
small collection of lines close together on the twig. If you count the
groups of lines on an apple twig, you can find out how many times the tree
has bloomed in the past.
Each apple blossom is held in a small green cup called a calyx. While
looking at the calyx from an overview it looks like a star because of its
sepals.
The apple blossom has a bright color and sweet fragrance that helps
attract bees. Bees help apples by spreading pollen. As bees fly from tree
to tree, pollen covers their hairy bodies. Then when they sit on another
blossom some of the old pollen rubs off and they collect new pollen. Soon
after the calyx tube has formed, a small green apple pops out. Then 130
to 145 days after bloom the apples are ripe. The next spring this cycle
starts over.
History of Apples
Apples have played a major role in historical agriculture. Apples
aren’t native to America but they came from Southwest Asia. In the 1800’s
two of the largest apple orchards belonged to George Washington and Thomas
Jefferson. Explorers, missionaries, settlers, and Indians all helped spread
apple trees to the new western territories. Apples were ideal for the west
because unlike most other fruits they could grow virtually anywhere. Colonists
knew how to dry them, stew them, and how to preserve them. The most famous
apple planter was Johnny Appleseed. He gave apple seeds to all who would
take them, planted the seeds wherever he could, fed many traveling settlers
and shared his experiences, joy, and seeds to all.
Malic Acid
Malic acid is a natural crystallized acid that can be obtained from
apples, rhubarb, plums, cherries, grapes, and some other fruits. Malic
acid also lives in all living cells but in smaller amounts, being one of
the intermediates of the Krebs cycle. The Krebs cycle is a series of biochemical
reactions occurring in small body in cells in the presence of oxygen by
which acetate, resulting from the breakdown of crop, is converted to carbon
dioxide and water, with the release of energy.
Malic Acid vs. Health
Malic acid is essential to human health, but too much of it can make
you sick. You can’t become deficient in it because the body produces malic
acid itself. Malic acid also helps prevent the risk of heart disease
Starch
Starch is a white powdery substance found in all green plants. Starch
can also be found in seeds, corn, beans, potatoes, in stems, and leaves.
Starch is a carbohydrate. Starch is a very important substance for both
humans and animals alike because when starch is digested energy is released.
During photosynthesis (green plant growth) sunlight changes the water and
carbon dioxide into glucose and oxygen. The plant’s cells quickly convert
the glucose into starch. Photosynthesis can be shown with this chemical
formula. 6 CO2 + 6 H2O => C6H12O6 + 6 O2
Starch vs. health
One third of our food intake is starch. You can find starch in
almost any food. Some food manufactures add starch to their products. You
get almost all of your energy from starch.
Brix
Brix is a measure of the percent solids in a given plant juice.
Some times Brix is expressed differently: Brix equals the percent of sucrose.
Brix varies mainly because of the quality of the plant. For example, a
bad tasting apple from poor soil will rank about an 8 or less Brix. On
the other hand, a full flavored, sweet apple from rich soil can rank a
24 or higher.
History of Brix
Professor A. F. Brix was a chemist in the 19th century. He was
the inventor of the refractometer, and the concept of Brix. The orchard
and vineyard owners were so pleased with his work they all got together
and decided to name it after him. Now some people still use the refractometers
that he invented twenty years after his findings of brix. A refractometer
is used to find the amount of sugar in a fruit.
Starch Test
The Starch-Iodine test is an sign of inner metabolic activity, because
iodine solution will stain the starch (not sugars) present in the apple
tissues. Starch remaining in the apple during the storage period is converted
to sugars that will improve the quality of the fruit. Iodine can show this
reduction in starch.
Titration
Titration is an analytical method in which a standard solution is used
to determine the concentration of another solution.
A pH meter is a specially designed voltmeter, which can be used to
measure the electrical potential difference between very high resistance
voltaic cells, under conditions of essentially, zero current flow in the
measuring circuit. A high resistance voltaic cell is created when
a glass electrode and a reference electrode such as a calomel electrode
are immersed in an aqueous solution
Refractometer
A refractometer is an optical instrument that measures the sucrose
concentration in a sucrose and water solution. When light enters a liquid
it changes direction; this is called refraction. The refractometer takes
the refraction angles and correlates them to the refractive index values
that have been established. Using these values, you can determine the concentrations
of solutions. Solutions have different refractive indexes depending on
their concentration in water
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BIBLIOGRAPHY
“Golden Delicious. ” Apple Varieties. January 7, 2004 http;//www. bestapples. com/varities/gold.html.
“Granny Smith. ” Apple Varieties. January 7, 2004 http;//www. bestapples. com/varities/granny.html.
“Red Delicious. ” Apple Varieties. January 7,2004 http;//www. bestapples. com/varities/red.html.
Appleman, Even H. "Iodine. ” World Book Encyclopedia, 1999.
“Apples. ” Microsoft Encarta Encyclopedia Deluxe. 2001edition. CD-Rom.
Redmond, WA: Microsoft Corporation, 2001.
Bachman, Robert L and Golden, Marsha. Malic acid, October 27, 2003
http://www. geocities. com/nutriflip/supplement/maliceacid.htm.
Beemer, Alyssa. Does Controlled Atmosphere Storage Affect the Malic
Acid and Starch Levels in Apples? October 27, 2003 http://www.Selah.k12.wa.us/SOAR
/sciproj2003/AlyssaB.html
“Brix’, January 5, 2004 http: www. crossroads. ws/brixbook/Bbook.htm
“Brix”, January 5, 2004 http://bensonlab. byu. edu/testing_techniques/manual/brix,hml
Iodine testing. September 26, 2003 http://www. orchardproject. org/starch_test.htm.
Jamieson, Kay. “Starch. ” The World Book Encyclopedia. 1999.
Kentucky Apple Interacted Crop Management Manual. November 15, 2003
http://www. uky. edu/agreculture/Ipm/appleipm/hort. php.
Kohn, Bernice. Apples a Bushel of Fun and Facts. New York: Parent’s
Magazine Press, 1979 pages 5-55.
MacKenzie, Jill and Bedford, David. Starch-Iodine testing. University
of Minnesota Encyclopedia. 2001.
“Malic Acid” October, 29, 2003 http://www. Bartek. on. ca/malic_acid.html
“Malic Acid” October 29, 2003 http://www. pccnaturalmarkets. com/health/supp/MalicAcid. com
Malic Acid. November, 23, 2003 http://www. bartek. on. ca/malic_acid.html
“Malic acid” The Hudson Dictionary of Science January 1, 1998
“Malic Acid” December 13, 2003 http://www. geocities. com/Stephen_regal/basics.html.
Malic Acid. December 9, 2003 http:// www. geocities. com/nutriflip/Supplement/MalicAcid.html.
Morris, John, Refractometer. January 5,2003 http://www. johnmorris. com,
au/atagoextras/refactheory.htm
Morris, John, Brix. January 5, 2004 hptt://www. johnmorris. com. au/atagoextras/Brix.htm
Pennsylvania Fruit Production Guide. October, 14, 2003 http://tfpg. cas. psu. edu/part6/part61a.htm
Warner, Geraldine. Apple Maturity. January 29, 2004 http://www. goodfruit. com/link/sep-98/feature3.html
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ACKNOWLEDGEMENTS
I would like to thank the following people for helping make my project
possible
* My mom for all the help and money needed to do this experiment.
*Mr. Newkirk for all the time he gave me after and during school.
*Cely Dailey for mentoring me the whole way through this long
process and providing me with Tree Top research lab equipment.
*I also thank Tree Top in general, without which none of this
would have been possible.
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