Foam-based mustard essential oil microcapsules preparation, characterization, grilling application and comparison with emulsion microcapsules

Emulsion-based microencapsulation is the dominant form of encapsulating target components. Foam of emulsions is a neglected and important form of encapsulation due to its lower substance content, large specific surface area, and stable water-oil emulsion interface, which is equally feasible for drying and encapsulation. In this study, using the encapsulation of a small amount of mustard essential oil (MEO) as an example, the differences in physicochemical properties between foam-based and emulsion-based MEO microcapsules were evaluated by preparing protein (soybean isolate protein) and polysaccharide (sodium alginate) emulsion systems with a high amount of foaming, collecting the foams and drying (hot air drying and freeze-drying). The effects of the powders on barbecue seasoning were also tested on this basis. By comparison, the foam microcapsules have an irregular micro-particle structure, particle size, and differences in wall properties, leading to significant differences in particle surface oil content, water solubility, flowability, and release characteristics. Still, the microcapsules all provide enhancement in the seasoning of roasted meat. Moreover, by image tracing and contouring of the microstructure, the distribution relationship of the components in the foam microcapsules was also explained. These discussions provide a new insight into the preparation and application of foam microcapsules.