Novel multilayer microcapsules based on soy protein isolate fibrils and high methoxyl pectin: Production, characterization and release modeling

In this study, novel microcapsules were produced through the layer by layer adsorption of food-grade and plant-based polyelectrolytes, soy protein isolate (SPI) fibrils and high methoxyl pectin (HMP). The physical properties of the fibrils were investigated by TEM and AFM and the properties of the microcapsules such as size, uniformity, zeta potential, morphology, functional groups, modeling and the release kinetics of limonene were examined. The results revealed that SPI-fibrils had a thickness varying from 1 to 10 nm and strand like structure. SEM images showed that the microcapsules were spherical and the thickness increased by the number of layers which led to the improvement of shell strength. The FTIR results confirmed that HMP and SPI-fibrils were adsorbed layer by layer as the walls of microcapsules and presence of limonene was stable into microcapsules. By increasing the number of layers of the shell from 2 to 6, the release rate of limonene decreased significantly. The index n in Rigter-Peppas model indicates that the release mechanism of limonene from multilayer microcapsules followed a non-Fick law. This method of microcapsule production is very simple and could be readily industrialized, especially for the manufacture of food products for vegetarians.