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Science Project 2002  
Which Apple Type Changes in Sugar Content Most After Removal From Cold Storage?

Researched by Courtney H.


The purpose of this experiment was to measure the amount of natural sugar content change in three different types of apples over time out of cold storage.

I became interested in this idea when we took apples to the beach every year and I noticed that the apples tasted sweetest at the end of our trip. That aroused a question in my mind, so I decided to finally rest my curiosity.

The information gained from this experiment would help people know why and which apples are changed the most in sugar content when taken out of cold storage. 


My hypothesis was that red delicious apples would have a greater amount of sugar content change than granny smith will and golden delicious apples over time when removed from cold storage. I predict that the sugar content will increase.

I based my hypothesis on the fact that red delicious apples have a higher amount of sugar content in the first place seem to taste gradually sweeter during the time out of cold storage.


The constants in this study were: 
* The day removed from cold storage
* The device used to measure sugar
* The amount of juice that is squeezed from each apple
* The amount of juice that is dropped on the refractometer
* The number of each type of apple used to conduct the experiment
* The number of each apple used each day
* The temperature of the cold storage
* The source where the fruit was from
* The day the apples were picked
* The type of wipes used to clean the refractometer after every apple

The manipulated variable was the amount of days that the apples were taken out of cold storage. 

The responding variable was the amount of sugar change in the apples over time out of cold storage. 

To measure the responding variable I put three drops of each apples juice on the refractometer then read to see how much sugar was in each apples juice. For every day I tested three apples of each kind and obtained an average of the sugar content.

1 Refractometer
24 Ripe Granny Smith Apples
Ripe Golden Delicious Apples
24 Ripe Red Delicious Apples
1 Fruit Juicer
24 Pipettes
90 Three Ounce Cups
1  Marker
1 Sharp knife that is able to cut apples
1 Box of Kleenex


1. Gather Materials
2. Label three cups with the marker for each apple type as red apple #1, red apple #2, red apple #3, golden apple #1, golden apple #2, golden apple #3, granny apple #1, granny apple #2, and granny apple #3 for the juice to go into.
3. Use three apples of each type per day that you're conducting the experiment, which is twice a week, as evenly spaced as you can get the two days such as Monday and Thursday. 
4. Slice the apples that you are experimenting on into six equal pieces with the knife.
5. Make sure you rinse the knife with water before switching apple types so you don't get any of the apple juice mixed up.
6. Place the cup that matches up with the apple under the juicer spout to catch the juice.
7. Run as many slices as it takes through the juicer to get enough apple juice to test, (which is three drops.)
8. Collect the juice in the cup for each apple and carry them over to the refractometer.
9. Then gather three transfer pipettes, one for each apple type. 
10. Pump the transfer pipette five times before squeezing in some juice and before switching apples, just so the juice doesn’t have any remains of the previous apple.
11. Make sure to switch transfer pipettes when you switch apple types but keep the same one when switching apples within the same type.
12. Squeeze some juice from a cup into the transfer pipette so it is full and put three drops of it onto the refractometer, do the same for each cup of apple juice.
13. Then push the "read sample" button and the refractometer will show you how much brix of sugar is in the apples juice, be sure to record this information for your results.
14. When you are done testing three drops of juice, clean off the refractometer with water and a Kleenex, and make sure to rinse and dry thoroughly.
15. Once you have finished with your first apple type, run a slice of the next apple type through the juicer before actually testing that apple. Just so it clears out the remains of the first apple, you can discard the first slices’ juice when finished collecting it with an extra three ounce cup.
16. Repeat all the procedures above for each apple twice a week until the apples are gone, then record and graph your results.


The original purpose of this experiment was to measure the amount of natural sugar content change in three different apple types over time.

The results of the experiment show that all of the apples started around 12* brix. The golden delicious apples increased the most (to 12.93* brix.)   The red delicious apples decreased at first then increased (to 11.9067* brix.) The granny smith apples decreased, then increased, then decreased (to 11.0267* brix.) 
View my data and graphs


My hypothesis was that red delicious apples would have a greater amount of sugar content change than granny smith and golden delicious apples after removal from cold storage. I predicted that the red delicious apple sugar content would increase. 

The results indicate that this hypothesis should be rejected because the red delicious apple sugar content did not increase the most. 

Because of the results of this experiment, I wonder if each apple slice represented the true sugar content of that entire apple. Also, I wonder if similar findings would occur for other varieties of apples, like Fujis, Galas, and Romes. 

If I were to conduct this project again I should have tested each slice of each apple and then obtained an average for each apple.  I should have sampled more apples of each type so the results would be more reliable. I think that I should have made sure that each of the apples that I picked from the bins were equal in every possible way, for example, no bruises, no brown spots, very similar weight, etc. 

Research Report

Apples Health Value
 Apples are something almost every American enjoys. Apart from their taste they have great nutritional value. Apples are about 85% water. They also lower the cholesterol level of the consumer. Apples lower blood cholesterol if they are included in a diet, thanks to the constituents in the fruit. Apples can get rid of the fat that unhealthy foods put into a body. If someone were to eat a lot of apples in their diet, the fruit would crowd out the fat from high fat foods. Apples include pectin, which are fibers that are soluble and in most fruits and vegetables. A high pectin diet can also lower blood cholesterol. Apples include .78 grams of pectin in every 100 grams of fruit that is eaten. There are cholesterol lowering pills these days that only work with a low fat diet, but apples will do that for you without pills. The good thing is that the apples taste delicious and they lower cholesterol at the same time! The cholesterol lowering isn't the only benefit of apples, there are many more.  More than one apple a day is even better than just one; scientists are realizing. Apples and they improve health and longevity. Apples have Phenolic Antioxidants in them that block cholesterol damage. The antioxidant called Vitamin C provides eight percent of the average adult’s value of Vitamin C intake. Apples make Vitamin C more available in blood organs. People need Vitamin C because it helps you get well faster and it help your immune system work harder. Apples also prevent cholesterol oxidation. Cholesterol oxidation is chemically adding oxygen to things. The contents inside of an apple inhibit early reactions that lead to plaque in blood vessels. When you get too much plaque in your blood vessels, it could result in a heart attack. This concludes that the more apples someone was to eat, the better chance they would have to not have a heart attack.

Pectin is a substance that is found in the cell walls of many fruits and vegetables. The pectin combines other cells together and form sturdiness for the fruit of vegetable. It is used as a jelling or thickening agent in many processed foods such as relish, jelly, jam, and preserves. The only nutritional value that pectin has is dietary fiber. Pectin is a carbohydrate and includes starches and sugars. The type and amount of pectin in a fruit or vegetables depends on the species of food. Apples, currants, grapefruit, oranges, and plums have a great amount of pectin; the pectin that is contained in these foods is the type that causes gelling. When these fruits are cooked to make jelly or jam, the pectin inside of them forms a network of fiber and thickens the fruit. The pectin in other fruits, such as apricots, strawberries, pineapples and cherries do not thicken the fruit juices or cause them to gel, but commercial pectin can be added to the fruit juice to thicken it. The commercial pectin comes in the form of powder or liquid. This is made from the rinds of apples and citrus fruits, specifically oranges and lemons.   When you eat plenty of apples you receive plenty of pectin into your body system. Many studies have shown that the more apples you eat for a longer period of time, the more your cholesterol will decrease. Apples deliver a wonderful bonus benefit of pectin. Apples lower cholesterol more than the pectin content predicts.
Fructose is a sugar that nearly all fruits and many vegetables produce. Levulose and fruit sugar are also known as fructose; contains twice as much sweetness as table sugar, (sucrose.) Soft drinks, gelatin desserts, diet foods, jellies, and syrups all contain fructose to sweeten them. Fructose is the main sweetener in honey. Fructose and sucrose foods taste about the same, but fructose may contain fewer calories. Ice cream and candies get their smooth texture from fructose. It helps foods absorb moisture so they don’t go stale as fast. Commercially, fructose is produced as a liquid, a tablet, or a powder. 

Sucrose is the chemical name for common table sugar. Sucrose is a carbohydrate. It is a product in the process of food making in plants, also known as photosynthesis. Sucrose is widely used as a sweetener and is extracted from sugar beets and sugar cane. The chemical formula for sucrose is C12H22O11

Alternative names for glucose are grape sugar or blood sugar. Glucose is the main source of energy in most living organisms, including humans, and is a product of photosynthesis in green plants. Fruits such as grapes and figs contain large amounts of glucose, as well as honey. Glucose is about three fourths as sweet as sucrose; pure glucose appears as a white crystal. The chemical formula for glucose is C6H12O6. Glucose is a carbohydrate. Glucose is the most abundant monosaccharide, which is the simplest carbohydrate. This means that glucose is easy for your body to absorb into your blood stream straight from the intestine. Carbohydrates, such as starch and sucrose, need to be broken down into monosaccharides before the body can use them. After someone were to eat a large dose of carbohydrates, the amount of glucose in their blood stream would rise and stay up for a brief period in time. The extra glucose is removed from the blood and transported directly to the liver and muscles as a complex carbohydrate that is called glycogen. When someone needs fast energy the glycogen in the liver is converted back to glucose. When the storage space for glycogen is full, the extra glycogen may be turned into fat. Commercially, glucose is made from starch by treating the starch with acid under steam pressure. If all of the starch is converted into glucose, the product is sold and called dextrose. If the process is not complete, the starch is mixed with other sugar results to make corn syrup.  Manufacturers use dextrose and corn syrup to make many foods including candy, soft drinks, baked goods, and canned fruits.

Starch Metabolism of Apples
There are many reasons why apples change their form over time once removed from cold storage. First of all, the starches metabolize and break down into sugars. That is why apples get sweeter over time. The reason why they get soft and mushy over time is their pectin breaks down and they lose water, they get dehydrated. 



Barden, John A.  "Apples."  World Book Encyclopedia. 1999.

Fiegl, Dorothy M. "Glucose." World Book Encyclopedia. 1998.

Fiegl, Dorothy M. "Sucrose." World Book Encyclopedia.  1998.

Jamieon, Kay F. "Starch." World Book Encyclopedia.  1998.

Jamieson, Kay Franzen. "Fructose." World Book Encyclopedia. 1998.

Janik, Jules.  "Fruit."  World Book Encyclopedia.  1999.

"Michigan Apples."  Apples.  <>

"The Right Apple for the Job." Apples.


This science project could not have been possible without the help and assistance of the following wondrous people.

  • The scientists I worked with were John Baranowski and Sue Graf. They did an awesome job helping me pick a topic that I would enjoy and helping me conduct the experiment properly.
  •  I would also like to thank Mr. Newkirk and Mrs. Helms for helping me include everything in my project and for making sure that I stay. They also helped me figure out how to organize my board.
  • I would like to thank my mother and father for helping me transport to Tree Top to conduct my experiment twice a wee

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