Biology Research Vitamin C

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Biology Research – Vitamin C

Fruit and vegetables with the highest amounts of vitamin C

  • Peppers (red and green)
  • Guavas
  • Dark green leafy vegetables, Kale
  • Kiwi
  • Broccoli
  • Berries (strawberries, blackcurrants)
  • Citrus fruits (oranges and juice)
  • Tomatoes (cooked)
  • Peas
  • Papaya
  • Peaches

(1, 2)

Testing for vitamin C


A blue substance called 2, 6-dichlorophenolindophenol (DCPIP) acts as an indicator. It changes from blue to red/orange with acids but loses its colour in the presence of certain chemicals; one is ascorbic acid (vitamin C). DCPIP solution can be used to test for the presence of vitamin C in food.


Test tubes and rack

Glass rod



Food samples, juice

DCPIP solution



How different cooking methods affect vitamins in food

A Danish study showed that boiling for just 5 minutes caused 45 to 64 percent of vitamin C to be lost in broccoli. The most vitamins are retained when there is less contact with water and a shorter cooking time. Microwaving and stir-frying reduce vitamin loss because they cook food quickly. Deep frying also reduces vitamins in food; the high heat required for frying destroys heat-sensitive vitamins. (4)

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Ascorbic acid, or vitamin C, is an extremely unstable water-soluble vitamin. The vitamin C content of foods can be reduced by exposure to extreme cold, heat, light, lengthy storage and water. All forms of cooking reduce vitamin C levels in foods. However, boiling foods destroys the highest percentage. In a study published in the August 2009 issue of the "Journal of Zhejiang University Science," researchers examined five methods of cooking broccoli. The methods were stir-frying, microwaving, steaming, boiling, and a combination of stir-frying and boiling. The study concluded that after five minutes of cooking broccoli florets, using each method, boiling ...

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