Not all has been said about glucose oxidase/peroxidase: New pedagogical uses for a classical and robust undergraduate laboratory experiment.

The enzymatic determination of glucose in soft drinks, based on the glucose concentration measurement by means of the coupled reactions of glucose oxidase and peroxidase, has been implemented at the University of Malaga and optimized according to the Biochemistry and Chemistry undergraduate students' results and feedback throughout the last few years. This traditional and robust laboratory practical has been reformed, in the light of inquiry-based and interdisciplinary learning approaches, in order to optimize the students' formative achievements that now are not restricted to the learning of enzymology, but also integrates cross-curricular knowledge from chemistry and mathematics. In this experiment, inexpensive and feasible to be carried out in a single laboratory session, students have to make the decision of what method is the most suitable for a given analytical problem, anticipating situations that they will probably face throughout their professional careers. It not only illustrates basic issues related to the use of enzymes as reagents for enzymatic analyses and its application to food chemistry, but it is also used to put into practice some principles of statistical analysis and analytical methods evaluation. This can be achieved because students get results from two different enzymatic analysis protocols (kinetic and end-point methods) using a single reaction mixture. The measurement of glucose concentration in four carbonated soft-drinks, regular or sugar-free colas and tonic waters makes students deal with the presence of color interferences that should be either avoided or eliminated. Undergraduate students, having performed this experiment, have found it formative, interesting, and challenging. © 2019 International Union of Biochemistry and Molecular Biology, 00:(00)1-7, 2019.