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A promising technique for oil encapsulation in Ca-alginate capsules by inverse gelation was proposed by Abang et al. This method consists of emulsifying calcium chloride solution in oil and then adding it dropwise in an alginate solution to produce Ca-alginate capsules. Spherical capsules with diameters around 3 mm were produced by this technique, however the production of smaller capsules was not demonstrated. The objective of this study is to propose a new method of oil encapsulation in a Ca-alginate membrane by inverse gelation. The optimisation of the method leads to microcapsules with diameters around 500 μm. In a search of microcapsules with improved diffusion characteristics, the size reduction is an essential factor to broaden the applications in food, cosmetics and pharmaceuticals areas. This work contributes to a better understanding of the inverse gelation technique and allows the production of microcapsules with a well-defined shell-core structure. [ABSTRACT FROM AUTHOR]

Droplets millifluidic devices are efficient tools to produce monodisperse emulsions that can be used as template for the production of core-shell capsules. This work aims to develop an original alginate inverse gelation method to produce (micro)-capsules with a narrow size distribution using droplets millifluidic. Water-in-oil (W/O) emulsion dispersed phase containing Ca 2+ ions was directly injected into a continuous alginate phase to generate a secondary W/O/W emulsion. Due to the cross-linking of alginate molecules by Ca 2+ ions release, core-shell (micro)-capsules were formed with a very high oil loading. This study demonstrated for the first time the production of (micro)-capsules based on the inverse gelation mechanism using a simple millifluidic device. Monodisperse core-shell capsules with sizes ranging from 140 μm to 1.4 mm were produced by tuning flow rates of the continuous and dispersed phases and by varying internal diameter of the capillary tubing. The use of millifluidic devices paves the way to an integrative formulation of core-shell materials with very large characteristic sizes and new complex architectures. This should lead to the rapid emergence of new products in cosmetics or food where the texture and visual aspect play a key role for sale. [ABSTRACT FROM AUTHOR]