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Thread: Testing juice for vitamin C

  1. #1 Testing juice for vitamin C 
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    I hope this sort of question is allowed on this forum.

    Im in high school and I'm going to be writing an science paper soon, "APA" style.

    As I topic Iv decided to test for vitamin C in various juices. I plan on seeing how the amounts change over time, both refrigerated and unrefrigerated.

    Questions:
    1. Are there other chemicals that could easily be tested for in juices? I need plenty of data to write 2,000 words.
    2. Whats the best method for testing vitamin C in juices? I need something that will be able to test for small changes. There seems to be two methods Iv found: chemical test strips, and titration using iodine and startch. Strips: http://www.naturamart.com/perque-per...00-strips.html
    Titration:http://www.life.uiuc.edu/boast1/scie...s/vitaminc.htm
    3. Should I even expect Vitamin C levels to change much over time at room temperature? If not, any advice?


    Thanks!


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  3. #2  
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    I can't help with the testing. For it to change it would have to undergo some kind of chemical reaction and what would that be? You should do a little research on the internet using key words like "vitamin C shelf life" and find out what kind of changes to expect.

    I think it might be interesting to test different brands, fresh vs reconstituted, etc. You could check and see how it compares to the nutrition facts label on the carton.


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  4. #3  
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    Yeah I guess Vitamin C is a pretty stable chemical come to think of it. Maybe there's a chemical in juices that isn't so stable?

    Any other conditions I could test it under? It needs some sort of connection to reality(i.e no one puts juice in the microwave..)

    I would do testing simply of different products, but I think we're supposed to have a topic in which we can do multiple tests under different conditions.
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  5. #4  
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    Actually I edited my post because I looked it up and found it does change, due to oxidation. It would probably take a good while to detect with your home testing methods. As I said, do a little bit of research on the internet.
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  6. #5  
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    Thanks for your help :-D

    It looks like I'll do maybe three different orange juices: Plastic bottle, glass bottle, frozen can.

    So I'll be testing with three variables: Container type over time, heat, oxygen.

    For the first I suppose I'll leave one of each in the fridge and see what happens over a month.

    For the second I'm not sure. I could zap it in the microwave, but that wouldn't give me much real data about leaving juice out of the fridge. Maybe I could just leave all three out and call it "room temperature"? I'll probably leave it out for 1 week, then 2 etc etc, so I could easily get an average temperature. Also for this one I suppose I would only need to use the plastic bottled juice, not all three?

    For oxygen I'll use one of the three and leave it out for different amounts of time. And I guess I'll have to factor in evaporation to get accurate data.
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