Use of “Enzyme Powder” for Inquiry Activity on Starch Digestion in Elementary School Science

Abstract

In Japan, elementary school children have been using their own saliva for experiments on starch digestion when they learn about the digestion and absorption of food in science. In carrying out these experiments, the use of their own saliva is particularly important for pupils, because they can notice that their own digestive juices digest food inside their digestive organs. However, various germs may be contained in saliva, so that considerable caution is required to avoid infectious diseases. In addition, pupils dislike providing their saliva for these experiments. To overcome such obstacles, we have introduced a step, the preparation of saliva enzyme powder by the cold ethanol precipitation method, into the experimental procedure. Since the ethanol precipitation technique is too advanced for pupils, this step must be done by the teacher as a demonstration of the method. In our trial of the laboratory class on starch digestion, at first, a solution of the saliva enzyme powder, which the teacher had prepared, and a sheet of starch-containing paper were used to confirm that the saliva enzyme powder could digest starch. Then, pupils were given a question, “Do living things other than human beings also contain digestive aids to digest starch?” To find an answer to the question, pupils examined whether starch digestion would occur by the crude enzyme powders from germinating corn grains and “kome-koji” (malted rice with Aspergillus sp.) which were prepared by the same method as the saliva enzyme powder. In their experiment, small polythene bags and plastic straws were used instead of test tubes and syringes, respectively, to reduce the cost of the experiment. More than four fifths of pupils expressed affirmative impressions of the laboratory class.