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Research Question:- How does the time of boiling effect the amount of vitamin C in food

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Name : Mohd Haziq Al-Hakim Bin Hamirruddin Class : M08F Date : 18 July 2009 Title : Measuring the concentration of vitamin C Introduction:- Refer to Biology HL handbook page 159 Aim:- To investigate the effect of the time of boiling on the amount of vitamin C in food Research Question:- How does the time of boiling effect the amount of vitamin C in food Hypothesis:- The longer the duration of boiling of the citrus fruit, the lower the concentration of vitamin C Variables:- Independent : Time of boiling of the citrus fruit. Different boiling time is used which is 0min (fresh), 10 min and 1 hour. Dependent : The concentration of vitamin C. Controlled : Type of citrus fruit, volume of lemon juice, volume of DCPIP and volume of glacial acetic acid Apparatus and Materials:- Refer to Biology HL handbook page 159 Procedure:- Refer to Biology HL handbook page 159 Data Collection:- Quantitative Data:- Duration of boiling the juice Trial Volume of titrated juice, cm3 (�0.1) ...read more.


1 cm3 of the mixture contains mg of ascorbic acid 1cm3 of the original lemon juice contains mg of ascorbic acid However, unit must be in mg/100cm3 mg must multiply by 100 Where V - Average volume needed to decolourise DCPIP solution For fresh juice, = = (5.00/ 112.4) x 100 = 4.45 mg/100cm3 For 10 min, = = (5.00/ 151.6) x 100 = 3.30 mg/100cm3 For 1 hour, = = (5.00/ 180.0) X 100 = 2.78 mg/100cm3 Discussion:- 1. This experiment is conducted to calculate the concentration of ascorbic acid (C6H8O6) or vitamin C in different samples of lemon juice. To find the concentration, we titrated the sample juice against 1 cm3 of 2-6 dichlorophenol indophenol (DCPIP). The ascorbic acid contained inside the sample juice will bleach the dark blue colour of DCPIP to become a colourless solution because of its strong reducing agent properties. It is assumed that 0.05 mg of ascorbic acid will reduce 1 cm3 of DCPIP, a value which has been internationally standardised. ...read more.


Limitations and Suggestion Limitations Suggestions There are only two numbers of trials. This can lead to inaccurate of the result obtained. We can overcome this problem by increasing the number of trials for this experiment so that a more accurate result can be obtains. Drops of DCPIP used might not be standardised. Thus may result in variation of the colour change of the indicator. The amount of DCPIP solution must be standardized to avoid variation of colour obtained. The indication of colour change varies from an experiment to the other. Thus this could result in inaccuracies. Standard colour of solution should be prepared and the person that should swirl the flask must be the same so that accurate result could be obtained Conclusion:- From this experiment, it is known that fresh lemon juice has the highest concentration of ascorbic acid or vitamin C. This shows that the longer we cook a fruit, the less concentration of vitamin C will present as heat will destroy ascorbic acid in our foods. Hypothesis is accepted. Reference:- * Biology for the IB Diploma, CJ Clegg, Hodder Murray Publication 2007 ...read more.

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