How does age effect the vitamin C quantity in orange juice?

[cleocurtis]

Hi,

What grade level would this be appropriate for?
Any tips or suggestions to make experiment more impressive or interesting?
Any tips in general?

Thanks

[billeykamp]

What grade? Well, this involves chemistry, but it's simple chemistry. Access to a chemistry lab would be very useful.

The normal analysis for ascorbic acid (Vitamin C) involves titration with iodine. So you need access to iodine, but the quantities involved are small. Iodine requires careful handling and good practice, but I wouldn't think that is too much for a high school student. The titration is done with a starch indicator, and the end point is a very dramatic color change. I've done this titration many times, and I think it's fun.

It would help to start with some pure vitamin C, readily available, and be sure you can get the right answer with your technique.

It wouldn't surprise me if orange juice was variable in its initial Vitamin C content. Something you might check and report as part of the study.

As for the study itself, it is an interesting question having a rich folklore, so there should be some interest from your audience.

The destruction of Vitamin C is probably oxidation and the source is oxygen in the air. So, handling is critical. You will need to carefully record how the juice is handled, how often it's poured, how it's stirred and how often, how it's stored and at what temperature. Any handling is likely to promote aeration. The container is important. Full? Covered? Material? Oxygen diffuses through polyethylene but not through glass.

Since all these factors will influence the outcome, this could be a great way to learn technique and demonstrate that you have it!

[John Dreher]

Welcome to the forum cleocurtis. In addition to the helpful advice from billeykamp, you might also like to look at a few projects described on our site, for example

http://www.sciencebuddies.org/science-f ... p044.shtml

or

http://www.sciencebuddies.org/science-f ... p039.shtml

I found these and lots of other relevant materials by going to the main Science Buddies home page, at

http://www.sciencebuddies.org/

and entering "vitamin C" into the search engine. I would also strongly recommend that you read our sections on what makes a good science fair project. These are located at

http://www.sciencebuddies.org/science-f ... ndex.shtml

When you have decided just what you want to do, we are always ready to provide advice as needed.

Good luck!