It provides an interesting venue for a discussion of the significance of vitamins in enzyme structure and function. With scurvy being the model, the role of vitamins in the human diet can also be dramatized. Students first learn a simple titration technique and determine the relative vitamin C concentration in different orange juice preparations. They are then asked to design a lab which answers some question they have regarding vitamin C levels in foods. In cooperative groups of two, they design a scientifically controlled experiment to answer the question, conduct the experiment, collect data, and reach a conclusion based on their findings.
Materials needed for the lab are simple and inexpensive.
Depending on student generated lab designs, other materials and equipment will be necessary. Neither is more accurate than the other. The starch-iodine mixture is much cheaper. It can be made ahead and stored in a dark, cool place in two liter soda bottles and dispensed in liter containers at the lab stations. Both indicators vary from one preparation to the next, so an accurate measure of vitamin C is not really possible with this protocol.