Gliadin matrices for microencapsulation processes by simple coacervation method.

The aim of this study was to use a vegetal protein (gliadin) as a wall-forming component to produce microcapsules. The microencapsulation technique employed was the simple coacervation method and the encapsulated product was a non-food oil, hexadecane. Hexadecane was emulsified by a gliadin solution and the coacervation phenomena induced by adding a salt-solution in the continuous phase of the emulsion containing gliadin. The study of the coacervation conditions has shown that the richer in protein the continuous phase, the smaller the quantity of salt required. The main problem of the microencapsulation process by salting-out was to control the capsule size and the agglomeration of the capsules. This study succeeded in preventing the agglomeration phenomenon by adjusting the kinetics of the salt addition. When the feed rate of salt solution was very slow, this aggregation was considerably decreased. The suitable quantity of cross-linker (glutaraldehyde) to harden the microcapsules was determined by an electrophoresis method. The effect of different process parameters (gliadin concentration, quantity and addition kinetics of the coacervation agent, cross-linker concentration) was studied with regard to the final microcapsule characteristics (shape, size, composition, and mechanical resistance evaluated by a centrifugation test).