Alginate/soy protein system for essential oil encapsulation with intestinal delivery

Preparation of alginate-soy protein isolate (AL/SPI) complex beads containing essential oil of thyme was carried out by emulsification of thyme oil in aqueous sodium alginate solution blended with SPI solution, followed by atomization via electrostatic extrusion and gelification with calcium ions. The process parameters were optimized by variation of the alginate (1-2.5 wt.%) and SPI (0-1.5 wt.%) concentrations. Dry alginate-SPI particles exhibited wrinkle surface while shape distortion of hydrogel beads occurred with ≥1.5 wt.% alginate concentration, whereas SPI induced reduction of the particle size. Encapsulation efficiency of 72-80 % based on total polyphenols was achieved. In SGF the samples exhibited oil release of 42-55 % (due to matrix shrinkage and proteins degradation by pepsin activity), while the rest was delivered in SIF within 2.5 h simultaneously with swelling and degradation of the matrix.