Hey, Do You C My Potatoes? Determining Vitamin C Amounts in Cooked Potatoes *
|Time Required||Short (2-5 days)|
|Material Availability||Titration equipment and supplies are needed. A kit is available from our partner Home Science Tools.|
|Cost||High ($100 - $150)|
|Safety||Adult supervision is required. Iodine solution is poisonous. Avoid skin and eye contact. Wear chemical safety goggles and rubber gloves when handling the concentrated solution. For more tips, consult the Science Buddies Chemistry Safety Guide.|
As you know, vegetables not only taste good, but they are good for you. Many vegetables are a great source of vitamin C. Vitamin C is a water-soluble antioxidant that plays an important role in protecting the body from infection and disease. Humans do not make vitamin C on their own, so we must get it from dietary sources. Potatoes, like the ones shown in Figure 1, below, are one good source of vitamin C. Does cooking them affect how much vitamin C they have? In other words, if you boil a potato, is some of the vitamin C lost to the water that the potato is boiled in? In this cooking and food science project, you can investigate this and determine whether boiling a potato for a longer amount of time makes it lose more vitamin C or not. To quantify the amount of vitamin C, you will need to do some titrating.
Figure 1. Potatoes, like these large Russet potatoes, naturally have vitamin C.
Titration is a chemistry technique used to determine the unknown concentration of a chemical in a solution. For information on how to titrate, consult the references in the Bibliography and the science fair project idea Which Orange Juice Has the Most Vitamin C?. You could use the titration kit from our partner Home Science Tools and follow the Procedure for that science project idea, but instead of using orange juice, use liquid that potatoes have been boiled in for different amounts of time. To get a good vitamin C yield, you will want to boil the potatoes in as little water as possible (by filling a pot with a layer of potatoes and just barely submerging them all in water). To take your vitamin C measurements, you could take water samples after the potatoes have boiled for 10 minutes, 30 minutes, and 60 minutes, or you could try different time points. Let the liquid cool to room temperature before titrating it. You may also want to further dilute the Lugol's iodine solution to have more accurate readings (since potatoes have less vitamin C than orange juice). For more information about doing a titration, visit the Science Buddies webpage Titration Tutorial: Tips & Tricks for Titrating.
So how do you think cooking potatoes will affect how much vitamin C is left in them? Try this science project and do some titrations to find out for yourself!
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Last edit date: 2018-09-21
The following websites describe how to titrate vitamin C from vegetables.
- University of Canterbury. (n.d.). Determination of Vitamin C by Redox Titration with Iodine. Science Outreach. Retrieved October 7, 2008, from http://www.outreach.canterbury.ac.nz/chemistry/vitamin_C_iodine.shtml
- Helmenstine, A. (n.d.). Vitamin C Determination by Iodine Titration. Retrieved October 7, 2008, from http://chemistry.about.com/od/demonstrationsexperiments/ss/vitctitration.htm
- Wikipedia Contributors. (2008). Vitamin C. Wikipedia: The Free Encyclopedia. Retrieved October 7, 2008, from http://en.wikipedia.org/w/index.php?title=Vitamin_C&oldid=243741812
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