Does Cooking Food Destroy Its Potential Vitamin Levels?

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Updated on Oct 25, 2013

Grade Level: 9th - 10th; Type: Food Science


In this experiment, students will discover whether cooking food destroys potential vitamin levels. In this case, we will be focusing on vitamin C in citrus fruits. Students can, however, extend the experiment by testing other vitamins and foods as well!

Research Questions:

  • What role does Vitamin C play in the human body?
  • What happens if a person has a deficiency of Vitamin C?

When one thinks of vitamin C, pictures of oranges usually come to mind. That's because vitamin C is highly abundant in citrus fruits such as oranges, lemons, limes, and grapefruits.

Vitamin C is an ascorbic acid. Without it, organisms will not be able to function correctly. It allows essential metabolic reactions to be carried out in the body, which in turns, allows the organism to live healthily.


  • Citrus fruits- Oranges, Lemons, Limes, Grapefruits
  • Cornstarch
  • Iodine
  • Water
  • Beaker (if you are going to use a burner); Pot (if you are going to use a stove)
  • Bunsen Burner (or a stove)
  • Eyedropper/pipette
  • Several test tubes w/ rack
  • A white piece of paper
  • Pen and paper for notes


Preparing the Iodine Indicator

  1. Mix cornstarch (1 tbsp) and water together to make a paste.
  2. Add 250ml of water and boil for about 5 minutes.
  3. Using a dropper or a pipette, add 10 drops of the boiled solution to 75ml of water.
  4. Add iodine to the mixture until it turns a dark-purple color.

Comparing Vitamin C Levels

  1. Squeeze the juice out of your chosen citrus fruit into 2 separate containers. One container will be marked “heated” and the other “raw”.
  2. Heat the one who is mark “heated” until it boils.
  3. With rubber gloves, carefully remove it from heat.
  4. With a dropper, add 5ml of the iodine indicator solution to a standard 15ml test tube. Using a clean dropper (to prevent contamination), add 10 drops of the cooked juice into the test tube.
  5. Clean the dropper and do the above for the “raw” juice sample.
  6. Compare which one turns a darker color. The darker color means there is less Vitamin C present in that particular sample.

Terms/Concepts: Vitamin C; Metabolic function; Heat; Cooking; Necessary functions of organisms


Pauling, Linus(1976).Vitamin C, the Common Cold, and the Flu. W H Freeman & Co.ISBN0716703610.OCLC2388395.

Sofia PC is currently a college student with a deep interest in science who is aspiring to become a writer. She writes about all sorts of things across all subjects including, but not limited to; science, crafts, and fashion. She hopes to become a good writer so she can share her thoughts and experiences with the world and future generations.

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