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Does cooking deplete levels of vitamin C in vegetables?Featured science projectScience project video


Cooking is critical for our diets, as it helps us digest certain foods that may not be as gentle on our stomachs (easily digestible) in their raw form. Although proponents of healthy diets will often promote raw fruits and vegetables as being the healthiest, this may not always be the case. For this science fair project, you will determine whether cooking depletes or in fact concentrates the amount of Vitamin C in tomatoes and cherries, thus determining whether those foods are in fact healthier when cooked.


Fruits and vegetables lose Vitamin C when they are cooked.


You will be able to explain whether cooked foods contain more or less Vitamin C than their raw counterparts.

Scientific Terms

Nutrients, Vitamin deficiency, Scurvy, Absorb, Iodine,Titration


Vitamin C is a critical nutrient found in a variety of fruits and vegetables. Most commonly, we think of citrus fruits as great sources of Vitamin C ? oranges, lemons, grapefruits and limes ? but other foods are also full of Vitamin C. These include strawberries, cantaloupe and even sweet peppers.

Without enough Vitamin C, we would experience a vitamin deficiency that could lead to damaging health effects. One of the worst illnesses caused by Vitamin C deficiency is scurvy. This disease was common among seafarers during the 1800s and early 1900s; as a result, officials required sailors to consume a citrus ration of limes or lemons. Scurvy victims heal more slowly than healthy individuals, and their gums may begin to bleed. People with prolonged Vitamin C deficiencies may even suffer from slower bone growth.

Vitamins and minerals can easily be destroyed by the cooking process, though some foods actually become more nutritious when heated up. Did you know that cooking foods such as carrots, spinach, peppers and mushrooms may actually help humans absorb more nutrients as opposed to b eating them raw? Today, we will try to determine whether cooking actually increases the amount of available Vitamin C in two foods: tomatoes and cherries. We will find out whether cooked fruits and vegetables are more nutritious (in terms of Vitamin C) than raw fruits.

We know that iodine reacts with Vitamin C, so we will be adding it to raw fruit and vegetable extracts and then repeating the experiment with cooked food. Iodine solutions in water and starch lighten when they are exposed to large amounts of Vitamin C. That is, a purple iodine solution will get lighter if Vitamin C is present. This science project involves a titration test to determine the amount of Vitamin C in each sample.

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    Complexity level:
    Project cost ($):
    Time required:
    15 minutes to simmer fruit. 1-2 hours for set-up and completion of other lab steps.
    Material availability:
    Most materials can be found at a grocery store. Iodine can be purchased from a drug store or online. Graduated cylinders and lab hot plates can likely be found in a school laboratory or at laboratory supply store.
    Safety concerns:

    You should avoid ingesting iodine or getting it into the mouth or eyes. Burning hazard from cooking fruits. Food processors should be used under adult supervision.