Improving Hydrophilic Barriers of Encapsulated Compounds in Ca-Alginate Microgel Particles through a New lonotropic Gelation Method for Double Emulsion Droplets

摘要

The ability of encapsulation to protect hydrophilic-bioactive food compounds from harsh environments can be improved by strengthening the hydrophilic barriers of encapsulated food compounds in Ca-alginate microgel particles via the integration of oil into the microgels. This study introduces a one-step procedure to integrate water-in-oil (W/O) emulsion droplets directly into Ca-alginate microgels during the production using the impinging aerosols system. A water-in-oil-in-water (20 kg m(-3) alginate solution) (W-1/O/W-2) double emulsion was prepared using a high speed homogeniser followed by a microfluidiser. The microstructure of the W-1/O/W-2 emulsion was analysed using optical and fluorescence microscopy. The mean diameters of the W-1/O/W-2 emulsion droplets and resultant microgels were in the range of 27.8-65.4 mu m and 160-420 mu m, respectively. Food dye was used as a proxy for a hydrophilic food compound and its release from the microgels was significantly decreased when it was encapsulated in the W/O emulsion droplets. Based on the numerical analysis, the presence of the W/O emulsion droplets in the gel network reduced the degree of gelation of the microgel because the diffusion rate of Ca2+ cation in the microgel is reduced. The degree of gelation of the W/O emulsion droplets encapsulated microgel is 0.6 when the diameter of the droplet is reduced to 77.5 mu m and the concentration of CaCl2 solution is doubled to 22 kg m(-3). The potentiality of the impinging aerosol system to produce Ca-alginate microgels to encapsulate hydrophilic compounds with improved barriers is presented in this work.