Production of palatinose using Serratia plymuthica cells immobilized in chitosan.

In recent decades, the production of palatinose has aroused great interest since this structural isomer of sucrose has interesting potential. We describe a simple and effective method of immobilizing Serratia plymuthica cells in chitosan. The sucrose isomerase activity of immobilized preparations was enhanced many times by activation with fresh nutrient medium and subsequent drying. The preparations obtained were physically very stable with high enzyme activity and excellent operational stability. The effect of temperature, pH and substrate concentration on enzyme activity of the immobilized cells was investigated. Using immobilized cells, a complete conversion of sucrose (40% solution) into palatinose was achieved in 4 h in a "batch"-type enzyme reactor. The use of free or immobilized cells had no effect on the composition of the solution, in particular the sugar content. The palatinose content was 80% and that of trehalulose 7%.