PRODUCTION OF GELLAN-BASED MICROCAPSULES USING GLASS-CAPILLARY MICROFLUIDIC DEVICES

Biopolymer-based microcapsules are highly hierarchized structures containing an inner phase and a hydrogel shell. These microcapsules have gained considerable attention in the food industry due to their capacity to improve ingredient handling, to mask any undesirable flavors, or to protect different ingredients from chemical or physical degradation during storage or after ingestion. Biopolymer-based microcapsules can be obtained through external gelation of the middle phase - composed of an aqueous-based biopolymer - of an oil-in-water-in-oil double emulsion template (O/W/O). However, the preparation of O/W/O templates by conventional methods is not trivial and, in general, require two emulsification steps. To overcome this drawback, we used glass-capillary microfluidic device, which combines co-flow and flow-focusing in coaxial glass-capillaries, to produce double emulsion templates of microcapsules. The innermost, middle and continuous phases were composed by sunflower oil, low acyl gellan gum (0.5% wt) and Tween20 (2.0% wt), sunflower oil dispersion containing calcium acetate (1.0% wt) and polyglycerol-polyricinoleate (5.0% wt), respectively. We determined the range of flow rates that led to the desired intermittent and continuous dripping flow regime and how the microcapsule diameter and shell thickness changed with flow conditions. We produced microcapsules using FDA-approved ingredients with diameters from 130 to 260 µm and shell thickness varying from 3 to 20 µm. The proposed methodology can potentially be used in a broad range of applications for encapsulating, delivering, and controllably releasing hydrophobic active compounds in a water based medium.