Investigating Amounts of Vitamin C in Cut Fruits Left in Refrigerator over Time

Overview

Objectives I wanted to study how vitamin C content is affected by cutting fruits well ahead of consumption. I grouped the test fruit into two categories: fruit that visibly oxidizes and fruit that does not. I hypothesized that fruit that visibly oxidizes would losevitamin C at a faster rate than fruit that does not visibly oxidize. Methods To start my procedure, I made a reference sample using a known amount of vitamin C in water. Then I cut fruit into eighths and left the slices in containers in the refrigerator for varying numbers of days. (Uncut fruit were also placed in the fridge as a separate control.) On the testing day, I juiced this fruit and used a titration method that involved a reaction between iodine and cornstarch to find out the amount of vitamin C in the fruit. After this, I analyzed the data. I converted it to milligrams of vitamin C using the reference sample data, found the SEM for the values, graphed it, and conducted a T-test on it. I repeated this experiment by leaving fruit juice exposed in the fridge over time. Results I found that the vitamin C levels in all four fruits dropped over time. Of the oxidation-prone fruits I tested, Granny Smith apples lost 38% of their vitamin C content, while D Anjou pears lost 28% over the 8-day testing period. Of the fruits that do not visibly oxidize, strawberries and Navel orange showed a 19% and 24% reduction, respectively, in the amount of vitamin C over the test period. The vitamin C declining trend in all four fruits was statistically significant with P-values significantly less than 0.05. None of the whole fruits showed a reduction in vitamin C after 8 days in the fridge. Fruit juice showed an even bigger reduction in vitamin C content over the 4-day testing period. Conclusions It shows how vitamin C changes in pre-cut fruits, and helps people decide which fruits would be best not to store after cutting to maximize the vitamin C content.

Competition history

• CSEF 2019 Chemistry · Entry J0615

Resources

• CSEF project summary ↗

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