Microcapsules based on glycinin–sodium dodecyl sulfate complex coacervation

Abstract

Microcapsules processed by complex coacervation were prepared using hexadecane for the oil phase and glycinin (a soybean storage protein)–sodium dodecyl sulfate (SDS) as the main wall-forming material. The study underlines the essential role of SDS, which, by the way of [glycinin+-SDS−] insoluble complex formation, allowed the precipitation of proteins around oil droplets. Moreover, particular attention was attributed to the study of suitable conditions of glycinin cross-linking with glutaraldehyde. The reticulation step was performed at pH 4.0 and it was observed that the precipitated state of proteins increased considerably the efficiency of the cross-linking reaction. Analysis of the reactional medium after each main step of the process (emulsification, complex coacervation, cross-linking) allowed the follow-up and characterization of microcapsule formation. Optimization of different process parameters such as glycinin concentration, glycinin/SDS/glutaraldehyde ratios, pH and the kinetics of cross-linking allowed the encapsulation of the totality of oil and the use of more than 98% of initially introduced proteins for the microcapsule wall formation.