SAMPLE+LAB+REPORT

By Mrs. Kretschmer
 * Testing for the presence of starch in sample foods using the starch-iodine reaction**

__Introduction__ Whenever you eat food there is a high probability that the food contains starch. Some foods are obvious like bread, pasta and cereal but other are not as obvious like fruits and vegetables. By using the starch-iodine reaction, one can test a food for the presence of starch. This is only a qualitative test indicating the presence, not the amount of starch in the food. Different foods can be ground up into a pulp and iodine applied. The presence of a blue-black color will indicate a positive result.

__Experimental__ The materials for this lab include samples of potatoes, apples, corn flakes and white bread. A mortar and pestle, test tubes, water and iodine were also required. 1. Select each food and cut it into small pieces. Using the mortar and pestle, grind the food into a pulp. 2. Place a small amount of pulp into a test tube and add 2 mL of water. 3. Add one drop of iodine to the test tube. Cap and shake to develop the color. 4. Analyze your results.
 * = Potato ||= Blue-black ||
 * = Apple ||= Blue-black ||
 * = Corn flakes ||= Light Yellow ||
 * = White bread ||= Blue-black ||

__Analysis__ According to the lab results, some foods contain starch and others do not. The Potato, Apple and White bread all developed into a Blue-black color indicating a positive presence of starch. Since plain starch would react in this manner, it indicates that the starch complex is present. The corn flakes did not result in blue black, they stayed yellow. This indicates that starch was not present in this food.

__Conclusion__ By using the starch-iodine reaction, the presence of starch in food can be determined qualitatively. It was evident in the data table that starch was present in three of the four foods tested. This experiment supports the concept that iodine can be used as a testing reagent for the presence of starch.