The main purpose of this investigation is to distinguish the different amount of vitamin C there is in different fruit juices.

Introduction:

Vitamin C

Vitamin C is a water-soluble vitamin, which means you need it in your diet every day because it can't be stored in the body. The chemical name for vitamin C is “ascorbic acid”. Ascorbic acid is a good reducing agent and therefore it is easily oxidised. Vitamin C has a number of important functions. For example it: helps protect cells and keeps them healthy and also helps the body absorb iron from food. Vitamin C is required for the synthesis of collagen, an important structural component of blood vessels, tendons, ligaments, and bone Vitamin C is one of the most powerful antioxidants acting as a scavenger to neutralize harmful elements naturally occurring within the body and helps fight cell and tissue damage that could lead to disease Vitamin C also helps the body fight infection and may reduce risk of diseases, such as cancer. With vitamin C being such a useful substance to our bodies, finding good sources of vitamin C is important.

Many people today rely on vitamin supplement tablets. But fruit juices, vitamin-supplemented drinks, or vitamin supplemented foods may contain just as much vitamin C as a supplement table. Good sources of vitamin C are in citrus fruits like oranges and grapefruit. is also another great way to get vitamin C through fruits and vegetables.

DCPIP

DCPIP is a blue substance called dichlorophenolindophenol. It acts as an indicator and changes from blue to red with acids but turns colourless in the presence of certain chemicals, one of which is ascorbic acid (vitamin C). DCPIP solution can be used to test for the presence of vitamin C in foods and drinks. In this experiment were going to use 1ml of DCPIP and add the fruit juices drop by drop to see the disappearance of the blue color (it may even turn slightly pink).

Hypothesis:

The main purpose of this investigation is to distinguish the ...

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DCPIP

Hypothesis:

The main purpose of this investigation is to distinguish the different amount of vitamin C there is in different fruit juices. The aim of this experiment is to observe if commercially sold and popularly consumed juices are a good substitute for fresh fruits in terms of dietary in vitamin C. What this experiment expects to find out is exactly what kind of drink is better in terms of dietary vitamin. This experiment will investigate how much vitamin c is needed to decolourize 1cm³ of the blue dye known as DCPIP. My hypothesis is that fresh fruit should contain more vitamin C then fruit juices since they have not been transported and probably have spent less time on a shelf. Fresh fruits have also neither been heated like commercially sold drinks. This is important since vitamin C is heat labile. This means that vitamin C is susceptible to change and unstable or that the vitamin C can break down easily if exposed to high temperatures or is kept for a long time on a shelf.

Apparatus:

These materials will be needed for the experiment. For accurate results make sure all apparatus is clean thoroughly.

Variables:

Controlled Variable

Room temperature : should not be too high, otherwise the vitamin C content of the juices may be altered, since vitamin C is heat labile
Volume of DCPIP (1cm3)
Burette
Sample size of fruit juice

Safety Precautions:

During this experiment you will need safety goggles in case of spillage of DCPIP.
Vitamin C decomposes over time and on exposure to sunlight and oxygen. So try to avoid direct sunlight.
The dichlorophenolindophenol solution is unstable and needs to be freshly prepared each time it is used.

Method:

1. Set up the burette on the clamp and position it so that it is within eye level. Fill up the 50ml burette with the chosen fruit juice. Make sure the burette is closed to avoid spillage and to ensure accuracy you should certify that the tip of the burette is filled with the fruit juice.

2. Draw up 1ml of DCPIP solution into a 1ml syringe, and then release the quantity into a glass beaker. Place this beaker on top of the white tile which should be placed below the burette.

3. Carefully add one drop at a time of the juice from the 50ml burette in to the DCPIP solution. Stir the solution well with the glass rod to ensure that it is distributed evenly. Observe the colour change that may occur within the investigation. Once the blue solution has changed colour close the burette so that no more juice can be added.

4. Record the amount of juice left in the burette and minus it away from the total amount of juice you started with. This gives you the amount it took for the total amount of fruit juice to decolourize DCPIP.

5. Do the same with the other juices using the same amount of DCPIP solution. Comparison of the amounts of extract used will give some indication of the relative quantities of vitamin C in the juice samples.

6. The results then need to be recorded onto a table as this makes it easier to see which drinks have more vitamin c in if the results are all set out together. Furthermore, for each soft drink I would recommend that the procedure above is to be carried out three times for each one and then an average worked out as it is quite easy to overshoot the end point, so it is usually a good idea to repeat the above procedure to get a more accurate result. In addition, I would suggest keeping a different test tube for each solution, so that at the end of the experiment it is easier to make a comparison of the colour variations if any.

Results