Biology Vitamin C

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Investigating the vitamin C content of fruits and fruit juice

In this investigation, I aim to measure and compare whether there is a higher content of vitamin C in a fruit or a juice by measuring the volume of the sample required to decolourise a solution of dichlorophenolindophenol (DCPIP).

For this experiment, I aim to investigate and compare the content of vitamin C in the fruit against the fruit juice. The theory of this method is a titration with dichlorophenolindophenol (DCPIP). DCPIP is a redox dye and Ascorbic acid reacts with the DCPIP solution, changing the colour from a deep blue to either a pale pink or colourless solution. They react in a 1:1 state, so I can use the amount of ascorbic acid required to work out how much vitamin C is found in the other types of juice. This is known as a “redox reaction.” A “redox reaction” is also known as a “reduction-oxidation reaction”, it is when the oxidation number of the reactants is changed. (To change oxidation number, electrons must either be added to or removed from reactants.)

Vitamin C, which is also known as ascorbic acid, is a water-soluble vitamin. Ascorbate/ vitamin C is also a highly effective antioxidant, since it protects the body against oxidative anxiety and can prevent or slow oxidative damage to our bodies. But unlike most mammals and other animals, humans do not have the ability to make their own vitamin C. Therefore, we must obtain vitamin C through our diet. When our cells use oxygen, they naturally produce “free radicals,” which are chemicals that form naturally inside the body through the process of oxidation. These free radicals travel right the way through our bodies causing damage to our cells, organs and the body’s delicate chemical balance. “Free radicals” are highly unstable; therefore they damage cells by grabbing and donating electrons and this can cause the development on atherosclerosis. Extensive damage by these is thought to be a factor of developing CHD’s. Antioxidants neutralise these “free radicals” therefore prevent or slow down the damage that they cause. Even in small amounts vitamin C can protect essential molecules in the body, such as proteins, lipids (fats), carbohydrates, and nucleic acids (DNA and RNA) from damage by “free radicals”. Vitamin C can be found in Citrus fruits, that is why I chose to use a grapefruit to represent my experiment. Antioxidants are substances that are able of counteracting the destructive, but normal effects of the physiological process of oxidation in cell tissue. They are also nutrients as well as enzymes and are believed to play a role in preventing the development of CHD’s. (Until recently, the results of most future studies show that low or lacked intakes of vitamin C were associated with an increased risk of cardiovascular diseases.) Foods in high content of Vitamin C are required in an essential diet as they produce and release hydrogen atoms, which only have 1 electron, this is why scientists recommend us to maintain a good healthy diet.

In this experiment, I predicted that the actual Grapefruit would have a higher content of vitamin C, this is because it is well known to eat lots of fruit and vegetables, so I’m basing it on that, as fruits are healthy and Grapefruit is a citric fruit.

Fair test:
I will aim to keep this test as fair as possible. In order to do this, I will carry out a preliminary to point out any anomalies, and prevent them from happening again. I will also try and measure out all the solutions as accurate as possible making sure I keep my measurement based on the meniscus. I will make sure that 1 person is designated to 1 particular step, so mistakes will be minimal. I will use the same type of measuring equipment including the burette, pipette and measuring cylinders. Also, the fruit and fruit juice I am going to used will be the same. If some of the equipment has to be used again, I will make sure that it has been...
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