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Aim: To investigate the effect of cooking on vitamin C content in orange

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Date: 30th sept 2009 Title: An investigation on Vitamin C Aim: To investigate the effect of cooking on vitamin C content in orange Hypothesis: Vitamin C is destroyed by heating Prediction: The boiled orange juice will have lower vitamin C content than the fresh orange juice Biological Principle: Vitamin C is a strong reducing agent and can reduce DCPIP solution (a blue dye) to a colourless compound. The vitamin C content of the juices is measured by the amount of orange juice required to decolourize a fixed volume of DCPIP. The relative amount of vitamin C content of the juices is determined in this investigation. The independent variable is the orange juices with boiling and without boiling. ...read more.


8. Fresh orange juice was added drop by drop with into the DCPIP solution until the DCPIP solution was decolourized. 9. The number of drops of fresh orange juice needed to decolourize 1 ml of DCPIP solution was recorded. 10. Steps 7 to 9 were repeated for 2 times. 11. Steps 7 to 10 were repeated by using boiled orange juice. Precautions: 1. The juice should be collected from the whole orange and then divided into two equal portions. One portion is heated to boiling while the other portion is not heated. 2. Do not shake the mixture too vigourously. 3. Use the same dropper throughout the experiment. 4. ...read more.


Possible explanations are experimental errors, the hypothesis that vitamin C will be destroyed by heating is wrong, vitamin C denatured by heating can also decolourize DCPIP solution, the assumption that DCPIP solution is decolourized only by vitamin C and not by other substances in the orange juice may not be held 3. Biological significance: Cooked vegetables contain the same amount of vitamin C as raw vegetables. 4. Sources of errors: The end-point for decolourization might not have been detected accurately. The size of drops of orange juice from the same dropper might not be identical. Some drops might have adhered to the wall of the test tube instead of reacting with DCPIP. Conclusion: Vitamin C content in plant food is not affected by cooking. ?? ?? ?? ?? ...read more.

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