Which Fruit Has a Greater Rate of Dehydration?

Researched by Rochel B.
2002-03



Purpose

The 1st purpose of this experiment was to determine which fruit had a greater rate of dehydration.

The 2nd purpose of this experiment was to determine the percentage of weight loss for each fruit.

I became interested in this idea when my mother had sliced a variety of fruits and left them on the counter. The next day I went to eat them and they were dried entirely.

The information gained from this experiment would benefit fruit producers and fruit growers because they would know which fruits dehydrate the fastest and they might be able to prevent it. 
 


Hypothesis

My 1st hypothesis was that the apple would have the greatest rate of dehydration.

My 2nd hypothesis was that the apple would have the greatest percentage of weight loss.

I base my 1st and 2nd hypothesis on Fredrick J. Francis, a food industry scientist, who stated, "The apple has a rather large amount of moisture." Therefore, I think that the apple will dehydrate the fastest along with losing the most weight due to having a large amount of moisture.
 



 

Experiment Design

The constants in this study were: 

  • Humidity
  • Air temperature in testing environment 
  • Approximate mass of the fruit in test tray
  • Thickness of the slices
  • Amount of heat 
  • Amount of light 
  • Heat level in dehydrator
  • Fan speed in dehydrator
The manipulated variable was the kind of fruit that was being dehydrated. 

The 1st responding variable was the rate of dehydration and the 2nd responding variable was the percentage of weight loss.

To measure the 1st responding variable I determined the amount of time each tray of fruit took until the mass no longer decreased.
To measure the 2nd responding variable I subtracted the original mass of the fruit from the ending mass of the fruit, and then I would divide the difference by the original beginning mass of each fruit. 


Materials
 
Quantity Item Definition
1 Dehydrator
2 Clean dehydration trayís
1 Triple-Beam-Balance
1 Kitchen Knife
1 Timer
1 Calculator
4 Fresh flavored fruits
1 Garbage can
1 Clipboard with paper

 


Procedures

1. Label 2 test trayís A and B
2. Measure the mass of both trayís A and B
3. Slice each fruit (0.5 millimeters thick)
4. Arrange on each fruit tray a single layer of fruit 
5. Record initial mass of each tray of fruit, (including tray)
6. Dehydrate 
a. Set temperature 
b. Start timer
c. Check every 60 minutes and record mass
d. Rotate the fruit tray in a clockwise manner, each 60 minutes
e. Repeat step C until mass no longer decreases more than 1.0% of the original fruit mass
f. Record time
7. (Optional) Repeat steps 2-5 with same fruit for following trials
8. Repeat 2-6 for next type of fruit 
 



 

Results

The 1st original purpose of this experiment was to determine which fruit had a greatest rate of dehydration.

The 2nd original purpose of this experiment was to determine the percentage of weight loss for each fruit.

The results of the experiment indicated that the banana had the fastest dehydration rate of the tested fruits. The fruit with the slowest dehydration rate was the grapefruit. The banana took 6 hours, followed by the apple at 7 hours, orange at 10.6 hours and the grapefruit at 11.3 hours. 

However, the apple had the greatest percentage of weight loss, and the banana had the lowest. The apple had 88% of its mass evaporated, the orange had 86%, grapefruit with 85%, and the banana at 69% of its moisture evaporated. 

View my table and graph.



 

Conclusion

My 1st original hypothesis was that the apple, due to lots of moisture, would dehydrate fastest. 

The results indicate that the 1st hypothesis should be rejected because the banana dehydrated faster than any other fruit.

My 2nd original hypothesis was that the apple would have the greatest weight loss.

The results indicate that the 2nd hypothesis should be accepted because the apple did lose a large percentage of weight. 

Because of the results of this experiment, I wonder if I dehydrated more fruits would the banana still perform as it did and if I had used the a different method of dehydrating would the outcome change. 

If I were to conduct this project again I would dehydrate more types of fruit, and I would also conduct more trials for each type of fruit.



 
Research Report
Introduction
Dehydration is an important method of preserving food. Dehydrated fruit will store for long periods of time, where as fresh fruits will eventually spoil within 1 to 2 weeks. It provides fresh tastes after being stored for weeks and also gives a good source of vitamins, proteins, and other nutrients. 

Dehydration

Dehydration is when there in too much water and salt loss. When the water level falls below a certain area the salts will increase and will continue to do so until the water level reaches or surpasses its original level. When this happens it stimulates the drinking molecules and causes the need for water, known as thirst. When thirst happens it usually is treated with many different beverages rather than water, but however a portion is obtained by the foods and water from the body cells. Thirst is controlled by hypothalamus, part of the brain.

Dehydration occurs to many mammals as well as food products. In mammals dehydration causes dryness of throat, mouth, nose, and many mucous membranes. These drynessís usually occur in dry climates or during winter heating season. Dehydration most likely will occur in both men and women because there is no measurable difference between genders. Mammals lose water daily through urine, sweat, tears, and saliva. When we lose sweat it reduces the volume of blood, which will eventually increase the sodium level. Sweat also contains minerals such as sodium, potassium, and chloride. When these minerals mix they will decrease your overall blood volume. This also makes the heart contract more often in order to maintain a safe stroke beat. The heat produced from the heart increases your core temperature and mechanism, which is triggered to encourage evaporation. Eventually when it is all evaporated this condition becomes anhydrous. The fruit process of dehydration is similar to that of the mammals because it follows the same happenings. 

Hydration

Hydration is a chemical compound made of a definite amount of water and other substances. The evaporation of sweat during exercise enables us to maintain a safe core body temperature. As a mammal becomes more fit they will sweat more. This means that they will sweat sooner, for longer periods, and will sweat over a greater area of body. Sweat losses reduce the blood volume, which in turn, reduces the sodium concentration of blood. These physiologic changes stimulate the brain to trigger thirst. Both men and women exhibit a wide range of sweat responses and sweat rates. 

Sweat contains minerals such as sodium, potassium, and chloride, in addition to small amounts of other electrolytes. The fluid lost in dehydration decreases the overall blood volume. This requires the heart to contract more frequently and forcefully. There is no correlation between a personís age and how much they sweat. There is, however a correlation between fitness level and sweating responses, and the acclimation to heat. As work occurs, often via muscle contractions are generated. As the heat increases the core body temperature the sweat mechanism is triggered to encourage evaporation and to help cool the body down. 

Heat

When fruit is presented to heat the water molecules will gradually lose water and eventually dry up. Most fruits contain approximately 75% water and will spoil fairly quickly. In order to prevent spoilage the use of Osmotic dehydration is required. Osmotic dehydration can remove up to 50% of the fruits water level, most likely preventing quick spoilage. Osmotic dehydration has been around for more than 20 years being conducted by single unit operators, engineering aspects, industrial applicators, and technology economy runners. The main reason that the Osmotic dehydrator was put to use was to improve the food quality, and increase the economies potential. 

Orange

The orange is the most popular citrus fruit. It is known in the scientific world to be the Hesperidium. A Hesperidium is a citrus fruit that has a thick leathery rind with segmented pulp. The orange is valued for its delicious juice and its high content of vitamin C. Sixty-five million tons of orange is harvested throughout the world each year. Oranges grown in the United States are processed into frozen concentrated beverages. The orange provides quick energy, which is given off from the edible seed structure inside. 

Apple

The apple is the most popular pome fruit known to this day. Its firm, fleshy, structure is received straight from a flower. The Ancient Greeks first grew the apple in 300 B.C. Later the Ancient Romans brought with them to England apple seeds. They planted these seeds and unfortunately the Indians stole the apple trees, straight out of the ground. John Chapman (1774-1845) distributed seeds within the Indian village and was later called Johnny Appleseed. 

Banana

Banana is a nourishing fruit that grows in tropics and is popular throughout the world. People in the United States of America eat about 11 million bananas annually. The banana is rich in carbohydrates and also contains phosphorus potassium, and vitamin A and vitamin D. The banana is known for it sweet flavor and smooth yellowish skin. The Dwarf Cavendish, Williams, and Grand Nain are other popular varieties of the banana. Other countries take interests in the skin of the Red Jamaican because it is so thin that it is only accessible in the tropical areas. Bananas grow in hot damp climates and then thrive in rich, sandy loam soil that provides drainage abilities. 

The banana was first raised in Asia but is now raised in the tropics of Eastern and Western hemispheres. In 1860 the people in the Tropics ate bananas fairly often. Later the Merchants in Europe and the United States realized that exporting bananas could be a good profit, so they built a way of transportation. In 1890 the first firms were expanded and later had been replaced by international corporations. They controlled over $400 million world banana trades. Then in 1974, to balance the power between the two corporations they formed a banana growing country, which formed a Union of Banana Exporting. Finally in 1984 they together established an International Network for improvement of plantation.

Grape Fruit

The Grape Fruit is a large round citrus fruit that everybody in the West Indies all enjoys. In the West Indies they also drink the somewhat bitter tartness within the grape fruit. The Grape fruit received its name from some of the clusters that they produce.  The United States produce 45% of the worlds Grape fruit. We harvest 4.25 billion pounds of fruit yearly. The Grape fruit is said to originate in the West Indies and then in the early 1700ís scientists believed it had developed as a natural hybrid of the shaddock, or pummelo, a citrus fruit of the Southeastern, Asia. It was first planted in Florida in about 1820. By the 1900ís fruit was being produced and shipped throughout the United States.

Conclusion

Fruit is an important part of a healthy diet. Keeping fruit fresh and properly hydrated makes it more appetizing and nutritious. Dehydrating fruit is a good method of preserving it when refrigeration is not available or adequate. 

Bibliography
 
  • Barden, John A. "Apple" World Book Encyclopedia. 2002: CD ROM
  • Beck, Laurence H. "Dehydration" World Book Encyclopedia. 2002: CD ROM
  • DíAlessandro, Donna and Huth, Lindsay "Dehydration" What is Dehydration. June 2002
  • Janick, Jules "Fruit" World Book Encyclopedia. 2002: CD ROM
  • Lombardo, Peter V. "Publication of apple slices" Osmotic Dehydration
  • Marc Le Maguer, John Shi. "Osmotic treatment of foods" Osmotic Dehydration
  • "Osmotic." Dehydration of fruit.  November 25, 2002 http://www.barc.ernet.in/webpages/technology/osmotic.html
  • Quinn, Elizabeth "Hydration and Dehydration" Sports Medicine Quiz. 2002 http://www.sportsmedicine.about.com/cs/hydration/
  • Rock, Peter A. "Hydration" World Book Encyclopedia. 2001: CD ROM
  • Wardowski, Wilfred F. "Orange" Microsoft Encarta Encyclopedia. 2002: CD ROM

Acknowledgements
 

  • I would like to thank the following people: 
  • My mother, for picking me up after late science classes and helping me with phrases of the experiment.
  • My brother, for helping me pick out the fruit.
  • My Advanced Science teacher, for hosting after school science classes allowing me to complete my project and for loaning me the technology to make this experiment possible.
  • My immediate science teacher, for allowing me to use the classroom computers during class time.

 
 
 


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