Experiences

Detecting starch in food

Roberto Checchi

Italy

Vocational School

Biology

Teaching in class, Laboratory, Online Learning

Direct

Organic chemistry is one the hardest subjects: students live in a world dominated by images and they do not understand easily what they cannot see or touch. In this respect, the web is very useful. However students often remain passive spectators. For this reason, we have promoted some laboratory experiments to analyze foods that are highest in starches (we tried to include those foods that students usually prefer). Tincture of iodine can detect starches: iodine reacts with the coiled molecules and turns bluish-black. We analyzed different kinds of food pouring over them a few drops of iodine: if the product is rich in starches it turns a dark blue color.
When students found out that their diet is too rich in carbohydrates, they also started to consider the possible future effects of not eating a balanced diet.
Moreover, they realized that starches need to be digested into glucose, since only glucose can reach the cells and be a source of energy for cellular respiration.
Then we used an interactive white board to make a concept map describing the whole process: digestion, assimilation and transport to the mitochondrial cells.