Vitamin C content of fruit juices

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Title                : The vitamin C content of fruit juice

Objective        : To investigate and compare the vitamin C content in various fruit juice

Introduction:

Vitamins are a group of complex organic compounds which play an essential role in animal metabolic processes but which the animal cannot synthesise. Vitamins do not provide energy however, in their absence, the animal develops certain deficiency diseases or other abnormal conditions. Vitamins together with proteins, carbohydrates, fats and mineral salts are essential constituents of the food of animals. Certain animals can synthesise certain vitamins. All animals which require vitamin D can synthesise it from ergosterol in the presence of U.V light. With the exception of vitamin D, the human body cannot make its own vitamins, and some cannot be stored. Therefore, one must obtain vitamins from a food on a daily basis. A person's diet must provide all the necessary vitamins.

Vitamin C or Ascorbic acid is a water-soluble vitamin. Vitamin C cannot be stored by the body as it is not a fat-soluble vitamin. Excess vitamin C leaves the body through the urine. Thus, we need a constant supply of vitamin C in our diet. The chemical compound of vitamin C is C6H8O6 while its IUPAC name is 2-oxo-L-threo-hexono-1,4-lactone-2,3-enediol.

Image 1: 3D structure of vitamin C              Image 2: 2D structure of vitamin C

Vitamin C is essential for the growth and repair of tissues. This is because vitamin C is required in the synthesis of collagen which is an important protein in blood vessels, skin, tendons and ligaments. Vitamin C also plays an important role in the healing of wound and the repair and maintenance of cartilage, bones and teeth.

Not only that, vitamin C is also a strong antioxidant. Antioxidants are nutrients that block some of the damage caused by free radicals, which are by-products that result when our bodies transform food into energy. The build up of these by-products over time is largely responsible for the aging process and can contribute to the development of various health conditions such as cancer, heart disease, and a host of inflammatory conditions like arthritis. Antioxidants also help reduce the damage to the body caused by toxic chemicals and pollutants such as cigarette smoke. Vitamin C also plays a vital role in detoxification, aids ferum absorption and improves resistance to infection.

As all other vitamins, the human body only requires vitamin C in relatively small quantities as compared to macronutrients such as carbohydrates, proteins and lipids. Men require 90mg of vitamin C per day while women require 75 mg of vitamin C per day. However, the absence of vitamin C can cause deficiency diseases. Vitamin C is important in the formation of connective tissues in the body such as bones, teeth, skin and lining of blood vessels. Scurvy is a disease resulting from the deficiency of vitamin C. Scurvy leads to the formation of spots on the skin, bleeding from the mucous membranes such as nosebleeds, painful joints and bleeding gums due to poor collagen formation in the body. A person who is lacking in vitamin C is also more likely to be affected by cardiovascular diseases as atherosclerosis may develop when the lining of the artery is damaged. Other symptoms of vitamin C deficiency includes rough, dry, scaly skin, epithelial haemorrhages, delayed wound healing and impaired immunity making one more susceptible to infections.

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Good sources of vitamin C from vegetables are broccoli, Brussels sprouts, cauliflower, cabbage, green leafy vegetables, green and red peppers, chillies, watercress, parsley, sweet and white potatoes. Tomatoes, blackcurrants, strawberries, blueberries, cranberries, pineapples, kiwi fruit, papaya, mangoes, guavas and citrus fruits are also excellent sources of vitamin C.

Image 3: Examples of good sources of vitamin C  

DCPIP solution may be used to investigate the amount of vitamin C in a solution. 2,6 dichlorophenolindophenol (DCPIP) is a blue chemical compound that is used as a redox dye and indicator for vitamin ...

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The writer has produced a clear and well-written account of an investigation into relative vitamin C concentrations in fresh and commercial fruit juices. While much of the report reflects good scientific practice, there were, however, a number of shortcomings that need to be addressed before this can be considered A-grade standard work. [1] The choice of juices to be tested needed to be justified. Furthermore, data from manufacturers together with researched values for vit. C concentrations in these juices should have been discussed prior to testing. [2] The hypothesis was not fully supported by research. [3] Controlled variables were not fully identified and dealt with. [4] The method used to construct a standard curve was very inaccurate - although this was commented on in the evaluation. [5] Anomalies were not identified. [6] The discussion of results was rather brief and did not really address the difficulties of comparing fresh and commercial juice. These are common weaknesses in investigation reports and students aiming for the higher grades need to address all these issues in their work. In this particular case, it would take a relatively small effort on the writer's part to rectify the shortcomings and turn this into a high quality piece of A'Level work.