Experiment 9 Vitamin C PDF

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Experiment 9 vitamin C...

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Concentration of KIO3 in 500 ml: 7.6168*10^-4 Control: Average volume (ml): 31.18 Concentration: 0.00285 M Mg of Vitamin C: 12.55 30 Average volume (ml): 31.01 Concentration: 0.00283 M Mg of Vitamin C: 12.48 100 Average volume (ml): 30.99 Concentration: 0.00282 M Mg of Vitamin C: 12.47

Abstract: The amount of ascorbic acid in a Sunrype apple juice was determined by titration with potassium iodate. Titrations were performed at varying temperatures to access the degradation of vitamin C when Sunrype apple juice is exposed to higher temperatures. At higher temperatures, the amount of ascorbic acid in the apple juice decreased by a small amount. Introduction: Ascorbic acid or vitamin C is an essential nutrient contained in most fruit juices. Because world consumption of juice is on the rise research is being done to maximize the number of nutrients within these juices. Methods today to preserve shelf life involve heating up the fruit juices which has been shown to degrade the number of nutrients within the juice (Ordonez-Santos, 2019). In this study, the amount of ascorbic acid has been determined in samples of apple juice at varying temperatures. The research has been conducted to assess how higher temperatures affect the amount of vitamin C in samples of Sunrype apple juice. At higher temperatures, vitamin C amounts should undergo degradation. To determine the amount of degradation, samples were titrated with potassium iodate. Experimental: Samples of Sunrype apple juice were purchased from a grocery store and stored at room temperature until the analysis was performed. The concentration of potassium iodate with which to titrate it, was determined by the fact that Sunrype apple juice contained 90 mg of ascorbic acid for every 250 ml of juice. Apple juice samples were quantitatively prepared, EDTA was added before heating the samples to bind to any metals within the juice. Deionized water was added to the sample to dilute it, starch was added as an indicator as well as HCL and KI. Samples were heated on a hot plate. Titrations were performed until the endpoint was reached, indicated by a pale blue color.

Results: Table 1: Amount/Concentration of Ascorbic Acid

Control 30℃ (25℃)

40℃

50℃

60℃

70℃

80℃

90℃

100℃

Conc.

Moles/L (*10-3)

2.854

2.834

2.973

2.981

2.959

2.936

2.939

2.975

2.833

Mass

Mg

12.55

12.48

13.09

13.13

13.03

12.93

12.94

13.10

12.47

Discussion: The amount of ascorbic acid in Sunrype apple juice was determined to analyze the effects of temperature on vitamin C degradation. The experimental results show very little decreases in vitamin C content after heating the samples. At varying temperatures, the titrations performed also showed similar amounts of vitamin C as the control. This is most likely due to the fact that Sunrype pasteurizes their apple juice, meaning that the samples have already been heated to high temperatures in the factory in order to kill off any bacteria. Nonetheless, the results do show small decreases in vitamin C content, because heating the samples would have degraded the amount of ascorbic acid even more. Additionally, vitamin C degradation has already occurred from the results of the control samples. The results of the control samples showed that about 12 mg of vitamin C exists in 25 ml of apple juice, which is only about 72 mg of vitamin C for 250 ml of apple juice; which is lower than the content stated on the carton. With samples that have not been pasteurized the results could be improved and likely more degradation of vitamin C would be recorded. Conclusion: Vitamin C content in apple juice tends to decrease when heating to higher temperatures. The samples used were pasteurized, therefore the experimental results indicated very small decreases in ascorbic acid. Bibliography: Ordonez-Santos, L.O.; International Journal of Food Science and Technology. 2 019, 55, 201

Appendix Mg of Vitamin C for 30℃ titration 0.03101L (average volume titrated) * 7.6168E-4 (conc. of KIO3) = 2.3612E-5 moles 2.3612E-5 * 3/1 (stoichiometric ratio) = 7.0836E-5 moles of ascorbic acid 7.0836E-5 moles * 176.12 g/mol (ascorbic acid molecular weight) = 0.01248 kg Concentration for 30℃ titration 7.0836E-5 moles of ascorbic acid / 0.025 L (apple juice) = 0.002834 M...