What is the Effect of Heat on Vitamin C?

Researched by Bryan T.


The purpose of this experiment was to determine if increasing temperatures damage Vitamin C more.

I became interested in this idea because food and nutrition have interested me for the past year or so.

The information gained from this experiment may be used to help people to cook items containing Vitamin C at a temperature that won’t totally destroy it. 


My hypothesis was as temperature increases, Vitamin C content would decrease.

I base my hypothesis on the article from Compton’s Encyclopedia, "Vitamins/Vitamin C" 1995 that states ‘Vitamin C is water-soluble and is easily destroyed by heat.’

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The constants in this study were:

-The same amount of juice
-The same amount of water
-The same size of glass
-The same of vial
-The same size of graduated cylinder
-The same kind of orange used to make orange juice
The manipulated variable was the temperature of the juice containing Vitamin C.

The responding variable was the amount of Vitamin C in the juice. 

To measure the responding variable I titrated the indophenol with Vitamin C. The number of drops of juice needed to turn the indophenol clear determines the amount of Vitamin C left in the juice. 

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12 oranges
4 cups
125 mL indophenol
1 eyedropper
4 vial
1 25 mL graduated cylinder
1 pan
1 metric thermometer

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I. Preparation
1. Slice two oranges in half and squeeze the juice out.
2. Fill the graduated cylinder up with juice (25 ml). Pour it into the cup labeled 80°.
3. Repeat step 2.
4. Fill the graduated cylinder up to 5 ml with juice. 
5. Repeat 1-4 until each glass has 55 ml.
6. Take the indophenol. Pour it up to 10 ml into the graduated cylinder.
7. Pour the 10 ml into the vial.
8. Repeat steps 3 and 4 again for each vial.
9. Fill the pan up with water. 
10. Put the thermometer into the juice.
11. Set the cup labeled 80° into the water, since it will take longest to cool down.
12. Put the pan on burner.

II. Experiment
13. Turn the burner on.
14. Wait for the juice to reach the temperature of 80° Celsius.
15. Maintain 80° for 10 minute.
16. Repeat steps 10-15 for the temperatures of 60° and 40°.
17. Take the cup that was room temperature, or 20° Celsius.
18. Wait for the juice to cool down to 20° Celsius.
19. Take the dropper.
20. Fill it with juice.
21. Drop the juice into the indophenol.
22. Swirl the indophenol.
23. Repeat until the indophenol is clear.
24. Repeat steps 19-23 for 40°, 60°, and 80°.
25. Record data.

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The original purpose of this experiment was to if increasing temperatures damage Vitamin C more.

The results of the experiment were that the various temperatures did not damage Vitamin C at different rates. The first, second and third trial for 20° took 13 drops. The first trial for 40° took 14 drops, the second one took 12, and the third one took 12. The first, second and third trial for 60° took 13 drops. Trial one for 80° took 14 drops, 11 drops for the second trial, and 13 drops for the third trial. All the averages came out as 13 drops.

See the table and graph.

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My hypothesis was as temperature increases, Vitamin C content will decrease.

The results indicate that this hypothesis should be rejected. The temperature does not effect the amount of Vitamin C left in the juice. 

Because of the results of this experiment, I wonder if the amount of time the Vitamin C is left exposed to air would effect the amount of Vitamin C content in the juice.

My findings should be useful to cooks who want to keep their food healthy (like keeping the vitamins and minerals in it), but want it to be cooked thoroughly.

If I were to conduct this project again I would try to be more accurate with my temperatures,  try to use closer to the same size of drops, have more trials, keep the juice at the high temperatures for a longer period of time, and I’d use a different kind of juice.

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Human health is very important to our survival. Vitamins help humans maintain a healthy diet. Specifically, Vitamin C prevents scurvy, and helps to maintain healthy gums, strong bones and strong teeth. Heat is known to destroy Vitamin C.

Vitamin C

Vitamin C is an organic compound of carbon, hydrogen, and oxygen. It can be found in many things: oranges, limes, lemons, cantaloupe, raw cabbage, strawberries, tomatoes, spinach, other leafy vegetables, or other citrus fruits. Cow’s milk is also a good source of Vitamin C, until pasturized.

A child from ages 1-10 should get 40-45 mg of Vitamin C. Adults and adolescents should get 50-60 mg. If a person has just gone through major surgery, had a serious injury, got burnt, or was in extreme temperatures, they would need Vitamin C more than an average human being. 

If a person is lacking Vitamin C, their gums will probably be sore, and they will probably bleed under the skin due to their capillaries. Or, if it is bad enough, they might get scurvy, a disease caused by Vitamin C deficiency. However, a person may prevent this by drinking orange juice, as it provides enough Vitamin C for most purposes. Humans, monkeys, guinea pigs, and bulbul (a Persian songbird) require a dietary source of Vitamin C.

Vitamin C is also called ascorbic acid. It is called antiscorbutic acid by physicians. 

 Metals, heat, water, air, light and the process of being canned can destroy Vitamin C. 


 Heat is the fast and rapid movement of molecules. It increases the rate of most chemical reactions, especially with oxygen.

 Vitamin C is damaged by heat by increasing its rate of oxidation.

Temperature is the measurement of heat. It may be measured in two forms: Celsius and Fahrenheit. 

 Sir Isaac Newton discovered the two laws of thermodynamics (the study of different forms of energy). The first law says that energy may be changed to a different form, but not created or destroyed.  Heat, light, chemical and electrical energy are all forms of energy.
The second law of thermodynamics states: "in all energy exchanges, if no energy enters or leaves the system, the potential energy state will always be less than that of the initial state." This is sometimes referred to as entropy.

 Vitamin C is important to human health, and many species need a dietary source to stay healthy. However, it is very delicate and easily destroyed by many things. Heat is one of these things. 

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Boehm, Robert F. "Thermodynamics," World Book Encyclopedia, 1998. 

Herbert, Victor. "Vitamin," World Book Encyclopedia, 1999.

"Vitamins/Vitamin C," Comptons Encyclopedia, 1995.

"Asorbic Acid," Encarta Encyclopedia, 2000.

DiPalma, Joseph R. "Vitamins and Minerals," Academic American Encyclopedia, 1998.

Daniel, Louise J. "Vitamin C Contents of Some Common Foods," Encyclopedia Americana, 

Farabee, M.J. "Laws of Thermodynamics," available [online] at http://gened.emc.maricopa.edu/bio/BIOBK/BioBook.Enerl.html 

"Vitamins," The New Good Housekeeping Family Health and Medical Guide, 1999.


I would like to thank the following people for their help with my science project.

  • Mr. Newkirk for providing me with the indophenol.
  • My mother who helped (and nagged at) me to cut the items for my board straight, for buying the oranges for my experiment, and making me make every measurement and temperature fairly accurate.
  • My father who took me to the store at 7:15 PM to buy some rubber cement for my board, which was due the next day.

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