Starch+in+some+food

**__ Objective: __**
 * __ TESTING FOR STARCH __**

.- To describe simple chemical tests for the biomolecules of living organisms. **__ Background: __** If we want to know whether or not a particular type of molecule (in this case starch) is present in a substance, we can carry out a simple test. To test for starch, a few drops of **iodine solution** are added to the unknown solution (or food), and the mixture is gently shaken. A deep **blue-black** colour is a **positive result** (It means that starch is present). A control is needed to make sure that results are valid. == .- To show that the test is working properly, a solution that is known to contain the substance is tested, (for example, the **iodine solution** is used with potatoes, food that is known to contain starch) ==

.- __Food fraud, defined as " the deliberate substitution, addition or misrepresentation of food, food ingredients or food packaging made about a product for economic gain".__
**__ Materials: __**** (__What do we need?)__ ** ** .- Iodine solution ** ** .- Different foods (potatoes, rice, bread…..) ** ** .- An eyedropper ** ** .- A container ** ** __Procedure:__ ** 1.- Get a portion of each food (starting with rice and potatoes) and put it in a little container 2.- Add one or two drops of **Iodine solution** 3.- Observe how the **blue-black colour** appears, this colour is typical from the reaction between the iodine and the starch 4.- Now try with different foods, such as chicken or pork and confirm that they do not have starch. 5.- **Go on with the investigation:** It is not always the same. Sometimes, **__manufactures of hams add starch to their products. So, they can sell the ham for a higher price because it weighs more after the starch is added. You can investigate, with the same technique, if in some of the ham examples contain starch.__** **__ Analysis and Conclusions: __** 1.- Record your data in the following table. Put an “X” next to the food that contain starch.

2.- What type of biomolecule is starch? 3.- What is the function of starch?
 * ** FOOD ** || ** Starch is present (X = yes) ** ||
 * Rice ||   ||
 * Potatoes ||   ||
 * Boiled ham ||   ||
 * Peas ||   ||