Effect of concentrations of alginate, soy protein isolate and sunflower oil on water loss, shrinkage, elastic and structural properties of alginate-based emulsion gel beads during gelation

The aim of this study was to investigate the influence of concentrations of sodium alginate (0.5%–1.5% in the water phase of an emulsion), soy protein isolate (SPI, 0.5%–2.0% in the water phase) and oil phase (10%–40% in the emulsion) on the properties (including water loss, shrinkage, morphological, elastic, and structural properties) of emulsion gel beads during gelation (0–30 min). Gel beads were prepared with external gelation by dropping emulsions into CaCl₂ solutions using pipettes. The Young's modulus of emulsion gel beads kept increasing during gelation before reaching a plateau accompanied by syneresis (i.e., water loss), shrinkage, and structural tightening. SPI absorbed at the surface of oil droplets could prevent re-coalescence of droplets during gelation. Additionally, increasing concentrations of sodium alginate and oil increased the Young's modulus of gel beads. Water loss decreased with increasing contents of alginate, SPI and oil, and shrinkage could be diminished by increasing alginate and oil contents.