Comparison of Vitamin C levels in Oranges, Strawberries and Courgettes.

This method is used to make a rough comparison between the 3 samples in the title, regarding the amounts of Vitamin C.

ATTEMPT 1

EQUIPMENT

• Pretty much the same as yesterday.
• Additional conical flasks and beakers
• A burette

METHOD

1. Begin with the same amount of each sample. In our case, we used 25 grams.
2. Draw the liquid from the sample into a burette, and apply it drop by drop into DCPIP in a beaker.
3. The DCPIP solution should contain 0.25 grams and 50ml of water.
4. Work out how much sample liquid was required to make the DCPIP solution colourless.
5. Carry out the above stages for he other samples.
6. The comparing of the amount of sample used to completely change the DCPIP solution will give a rough indication of how much Vitamin C is in the food samples.
7. We tried to filter the sample, but that didnt work, as dropping the semi-solid fruit/veg would have wrecked the burette. We used 25 ml of sample.
8. Therefore, we then swapped the experiment around-dropping DCPIP solution into the sample. When the DCPIP no longer becomes colourless, we have our value, and can work out a rough idea of the amount of vitamin C.

RESULTS

ORANGE

It took 2 cm3 of DCPIP for the orange. Orange being a citrus fruit leads us to believe that we may have made an error-There was a slight confusion over the concentration of DCPIP solution.

STRAWBERRY

It took 15.5 cm3 of DCPIP until the reaction would no longer occur.

COURGETTE

It took only 1cm3 of DCPIP until he reaction wouldn't take place. We decided to leave the sample to stand for five minutes to see wether there was really so little vitamin C, or we had had an anomalous result in the previous experiment, that made it look like Courgette had more Vitamin C than it actually had. After 5 minutes there was still no reaction, which led us to believe that yesterdays result was anomalous.

THOUGHTS

We believe we might have made an error regarding the concentration of the Solution. We will repeat the experiment with 1/4 concentrations: 200ml with 0.5g of DCPIP

ATTEMPT 2 

We will add (cm3 at a time) DCPIP solution at a quarter concentration too 25 ml of each of of our samples.

EQUIPMENT

• 250ml conical flask
• 200ml glass beaker
• Mortar and pestle
• Distilled water
• Samples
• Glass rod
• Spatula
• Knife 
• Chopping board
• Knife
• Test tubes and rack 

The Method is much the same as previously detailed-create an extract of 25ml of each sample, and drop by drop add the DCPIP solution, noting down at what point the DCPIP solution fails to completely de colour.

RESULTS

ORANGE

Failed to de colour at 2.5cm3 of DCPIP

STRAWBERRY

Failed to de colour at 12cm3 of DCPIP

COURGETTE

Failed to de colour after 1cm3 of DCPIP