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Determination of Vitamin C in food

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Introduction

1.2 Determination of Vitamin C in food Vitamin C, L-ascorbic acid or L-ascorbate is an essential nutrient in humans. This is because we cannot synthesis the vitamin from glucose in the liver. It is thought that the absence of an enzyme l-gulonolactone oxidase from liver cells1 prevents humans from converting glucose into ascorbic acid. Ascorbic acid functions as an anti-oxidant in living organisms protecting the body against the effect of oxidative stress. Ascorbic acid is also important biologically as it is used as a cofactor in enzymatic reactions (no less than 8 reactions have been identified). These include the synthesis of collagen, a deficiency of which leads to the most notable disease of vitamin c loss, scurvy. Ascorbic acid forms the part of many important physiological functions. These include the syntheses of collagen, neurotransmitters, tyrosine carnitine and metabolism of microsome2. But most importantly it is known for its antioxidant activity. When free radicals are present in cells as high levels they are thought to have an effect on cardiovascular disease, high blood pressure and chronic inflammatory diseases3. It is thought that ascorbic acid reacts with these free radicals preventing them from causing damage to cells. How to measure the amount of Vitamin C in food One way to measure the amount of vitamin C in our food is to use what is called a redox titration. ...read more.

Middle

Y sec Concentration of ascorbic acid in food = Y/X x 0.2g per cm3 The above graph shows the relative concentration of vitamin c in the three fruits sampled. Conclusion The results show that out of the three fruits tested, the green kiwi fruit has the highest concentration of vitamin C 64mg per cm3; fresh orange has the second highest level of vitamin c with 36 mg per cm3 and fresh lemon last with 30 mg per cm3. These results match with that of published data for the expected amount of vitamin c in fruits. However despite this the quantity of vitamin c in each of the samples was significantly below published data. The amount of Vitamin c in the samples that I have measured was 67.0%, 64.8% and 65.0% respectively of the published data for the quantity of vitamin c, (as shown below) Fruit mg of Vitamin C per 100gr Grapefruit 31.2 Guava 228.3 Kiwifruit, green 98 Kiwifruit, yellow 120 to 180 Mango 28 Orange 53 Papaya 62 Rosehip 1,500 Strawberry 57 Tamarillo, red (Tree Tomato) 40 Lemon 46 Source http://www.ivannikolov.com/fitness-nutrition/articles/all/fruits-highest-in-vitaminc.html Evaluation The results clearly show that there is a significant difference between the expected amounts of vitamin c and the amount observed experimentally. As all of the amounts measured in this experiment are similar (67.0%, 64.8% and 65.0%). It seems to suggest that the error is a result of the experimental procedure for measuring the quantity of vitamin c and not in the manner that it has been carried out. ...read more.

Conclusion

J. Am. J. Med. 26: 740, 1959. 2. Gropper SS, Smith JL, Grodd JL (2004). Advanced Nutrition and Human Metabolism (4th ed.). Belmont, CA. USA: Thomson Wadsworth. pp. 260-275. 3. ? ^ Kelly, FJ (1998). "Use of antioxidants in the prevention and treatment of disease". Journal of the International Federation of Clinical Chemistry / IFCC 10 (1): 21-3. PMID 10181011. Appendix Fresh Orange Calculation for the concentration of vitamin c in food is as follows: Concentration of ascorbic acid solution = 0.2g per cm3 Time for ascorbic acid solution to change colour = 107 sec Time for fresh orange extract to change colour = 19 sec Concentration of ascorbic acid in food = 19/107 x 0.2g per cm3 x1000 = 36 mg per cm3 Kiwi Fruit Calculation for the concentration of vitamin c in food is as follows: Concentration of ascorbic acid solution = 0.2g per cm3 Time for ascorbic acid solution to change colour = 107 sec Time for kiwi extract to change colour = 34 sec Concentration of ascorbic acid in food = 34/107 x 0.2g per cm3 x1000 = 64 mg per cm3 Fresh Lemon Calculation for the concentration of vitamin c in food is as follows: Concentration of ascorbic acid solution = 0.2g per cm3 Time for ascorbic acid solution to change colour = 107 sec Time for fresh lemon extract to change colour = 16 sec Concentration of ascorbic acid in food = 16/107 x 0.2g per cm3 x1000 = 30 mg per cm3 ?? ?? ?? ?? UCI 205340050507X Candidate Number 0507 NEC student number SS121598 Page 1 ...read more.

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Here's what a star student thought of this essay

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Response to the question

Overall a good scientific essay. The introduction is fantastically written, but the conclusion and evaluation could use a lot more depth and improvements are suggested in point two. The response is written in a very clear and concise way.

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Response to the question

Overall a good scientific essay. The introduction is fantastically written, but the conclusion and evaluation could use a lot more depth and improvements are suggested in point two. The response is written in a very clear and concise way.

Level of analysis

The background provided behind vitamin C as an introduction goes into very deep scientific and chemical depth which is great to be seen in an essay. The scientific terms used are presented to a high level of clearness and understanding of the topic. The risks evaluated by the student and the improvements suggested are quite average, and the student could have identified other risks associated with the experiment and better improvements. No-pre scientific tests are done which would increase the candidates mark to identify any confounding factors or biases and how the student would take this into account whilst setting out the experiment. The student could also improve by making a null hypothesis. The conclusion is adequate and the use of comparison against published values is good. The candidate could have used correct cm cubed terms, and could have improved their evaluation by calculating percentage errors in the equipment used and there are no possible improvements to the experiment suggested.

Quality of writing

One or two spaces between words are missing due to proof-reading errors. Other spelling, grammar and punctuation are all accurate.


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