Abstract
This study has the following two aims; First, development of a home-made turbidity meter consisting of a solar cell and a light emitting diode(LED), for use as a teaching material. Second, its application for estimating the rate constant of enzymatic decomposition of natural abundant polymers. This instrument outputs the electrical voltage corresponding to the turbidity of a dispersing sample solution during the reaction. Amylase and starch from sweet potatos were used as an enzyme and a substrate for starch decomposition reaction ; papain and skim milk for protein decomposition reaction. Calibration curves were obtained to evaluate enzyme capacity from the rate constant of the decomposition reactions of starch and skim milk. By using these curves, the enzyme capacity was estimated for several natural liquids such as saliva, familiar in daily life. As a result, we propose that our home-made turbidity meter is very useful to measure the rate constant of the decomposition reactions. Its easy operation as well as cheap price is useful for individual students to study the enzymatic decomposition reaction of natural abundant polymer.
