You Have to "C" It to Believe It: How Does Time Affect the Amount of Vitamin C in an Orange?

Overview

Objectives/Goals My objective was to use titration of orange juice with iodine to find when an orange contains the highest amount of Vitamin C after being picked, so that it would be the healthiest possible. Methods/Materials I started out by creating a starch indicator solution by heating water and adding souble starch. I also diluted Lugol#s 2% iodine solution so I could accurately measure the amount of Vitamin C in an orange. Periodically I would juice the oranges picked on day one and measure the amount Vitamin C they contained by titrating them with the diluted Lugol#s solution I made. All oranges were picked on the same day but juiced on different days. I repeated this process in three trials and used store bought oranges as a control group. Results The amount of Vitamin C in the oranges actually increased the first week from an average of 16.10 mg of Vitamin C on day one to 16.97 mg on day three and 17.80 mg on day seven. However, in the weeks following, the Vitamin C dropped to 14.27 mg on day fourteen and 11.97 mg on day twenty-one. Conclusions/Discussion My hypothesis that using an orange picked recently is going to have more Vitamin C than an orange picked a while ago was supported by my results. While it might be a good idea to not eat your orange right away after it is picked, make sure you don#t wait too long to eat it. Next time I might measure oranges of different sizes, and see if that affects the Vitamin C content.

Competition history

• CSEF 2015 Biochemistry/ Molecular Biology · Entry J0516

Resources

• CSEF project summary ↗

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