Development of immobilization and encapsulation techniques for bioactive molecules.

Bioactive molecules such as enzyme: aminoacylase I (EC 3.5.1.14), and natural colorants :anthocyanins extracts of red cabbage, red grape skin and curcuminoids extract of tumeric (Curcuma longa L.) were immobilized and encapsulated in polysaccharides. The enzyme aminoacylase was immobilized by (i) surface immobilization on chitosan beads and (ii) by complexation with chitosan for the production of L-phenylalanine from a racemic mixture of N-acetyl-DL-phenylalanine. The two immobilized enzyme systems were characterized in terms of thermal , stability, effects of pH and temperature, kinetic constants and operational stability. The activity and optimal temperature of immobilized enzyme were higher than those of the free enzyme. The immobilized aminoacylase by complexation with chitosan was a better system The activities were enhanced by about 400% at neutral and alkaline pH and at temperatures of 50 - 70 0 C. In addition, it afforded good operational stability when used as a plug-flow bioreactor and batch reactor. The natural colorants such as red anthocyanins extracts and curcuminoids extract were successfully encapsulated in calcium alginate beads and in chitosan beads respectively. The stabilities of anthocyanins and curcuminoids in the beads were comparable to those in solutions.