Preliminary study on microbeads production by co-extrusion technology

The present paper describes preliminary results on the development of a batch lab-scale co-extrusion device for the production of alginate beads as carrier for hydrophilic compounds. A dual jet of liquid core (aqueous solution of glucose or vitamin B12 or olive oil) and liquid shell material (aqueous solution of alginates differing for guluronic to mannuronic ratio) was pumped through concentric extrusion nozzles and droplets were formed by means of a rotating fluid jet cutter. The shell of the bead was then hardened in the hardening bath containing a calcium chloride solution. Optimization of the co-extrusion plant accounts for the management of the operative conditions within the hardening unit (incubation time, molarity of the gelling agent), and for the control of the surface-tension-driven breakup of laminar jets which was managed by varying the jet cutter - hardening unit distance. Beads enriched in vitamin B12, that were formed according to the best plant set-up, were tested for the bioactive release when stressed under thermal conditions simulating typical dairy products processes. Cyanocobalamin was retained at all.