(271d) Immobilization of Invertase in Calcium Alginate Gel Capsules and Determination of Batch Kinetics

Inverted sugar is an edible mixture of equal parts fructose and glucose typically produced by heating sucrose with water. This mixture is more desirable than sucrose because it does not crystallize due to its hygroscopic nature. The enzyme invertase, commonly isolated from Saccharomyces cerevisiae, is used to catalyze the hydrolysis reaction. Like many enzymes, invertase is time-consuming and expensive to isolate; therefore immobilization techniques have been developed to entrap the enzyme in porous gel capsules to make the process more efficient. Calcium alginate is a water-insoluble gel that can be safely made in the lab. This abstract outlines the procedure used to entrap invertase in calcium alginate beads. Additionally, once the invertase has been immobilized, a simple laboratory procedure to determine the kinetics of sucrose inversion in a batch system is outlined. The purpose of this abstract is to provide a methodology that can be used to create immobilized invertase gel capsules, and an analytical laboratory procedure that can be carried out by post-secondary students to produce calibration curves and determine the kinetics of invertase immobilization.

The work presented in this abstract outlines a junior/senior level chemical and biomolecular engineering laboratory module. In this module students immobilize invertase in calcium alginate gel beads using a technique that was outlined by Tanriseven and Dogan 2001 with a few modifications to ensure the enzyme will stay in the beads. The beads were refrigerated for one week and it was determine that their efficacy to convert sucrose to glucose and fructose was not affected over this period of time. The experiments were completed in 3 three-hour sessions (for a total of nine hours). In the first session, students created the calcium alginate gel beads. In the second session, a kinetics study was completed using batch reactors and commercial blood glucose meters to determine the amount of glucose present as a function of time in the reactors. And in the third session students filled a packed bed reactor with alginate beads and ran a simple experiment to determine the efficacy of the beads in a packed bed reactor system. Further work is currently being conducted to develop an analytical packed bed reactor model.

Using materials that are easy to find and relatively inexpensive, this lab introduces students to a variety of scientific concepts that can be explored to depths suitable for many different types of laboratory courses; development of a calibration curve, enzyme entrapment, batch reactions and enzyme kinetics can be taught with the laboratory experiment discussed in this abstract. This highly customizable experiment allows an instructor to introduce students to ideas ranging from basic scientific concepts like calibrating an instrument to big-picture industrial scale ideas of enzyme kinetics in packed bed reactors.

1. Tanriseven, A.; Dogan S. Immobilization of invertase within calcium alginate gel capsules. Process Biochemistry, 2001, 36(11), 1081-1083.
2. Hardee J. R.; Montgomery, T.M.; Jones, W.H. Chemistry and Flatulence: An Introductory Enzyme Experiment. Journal of Chemical Education, 2000, 77(4), 498-500.