Testing foods for starch. Circle the laboratory instruments you will need for this experiment.

Next to each name draw a sketch of the instruments above. Test tube Wash bottle Beaker Test tube rack Dropper

BACKGROUND INFORMATION Starch is a carbohydrate. It is found in plants BACKGROUND INFORMATION Starch is a carbohydrate. It is found in plants. Green plants make carbohydrates through photosynthesis. Starch is therefore in many foods, but also in other things as well, e.g. some paper. Starch is a white powder. Starch reacts with iodine to produce a blue or blue-black colour. It can therefore be used as an ‘indicator’, i.e. to test if starch is present in something. TRIGGER QUESTIONS: 1) Where do you find starch? 2) Where do you think starch comes from?

Equipment Test tube, beaker, glass rod, dropper, wash bottle, test tube rack Materials starch, potato, wheatmeal; iodine solution; distilled water. Procedure 1) Add 10 cm3 of water and some starch to a clean test tube. (Our sample) 2) Add 10 cm3 of water and some wheatmeal to a clean test tube. 3) Add 10 cm3 of water and some sucrose to a clean test tube. 4) Peel off the skin of potato.

Did iodine turn blue or blue-black? Was there starch in the item? Activity 5) Add a few drops of iodine solution to each of the items and observe the change of colour of the iodine (if any). Anything that turns blue-black contains starch. Record the results in a table: ITEM Did iodine turn blue or blue-black? Was there starch in the item? Wheatmeal Sucrose Potato