Multiple layers of whey protein and sodium alginate were assembled onto gelled alginate microparticles using electrostatic interaction. An experimental design was employed to evaluate the effect of the concentration of both hydrocolloids on the amount of protein that was adsorbed. In the first layer, a higher protein adsorption 32.5% w/w was obtained at pH 3.75. In the multilayered particle, the protein adsorbed reached 64.9% w/w. An analysis of protein solubilisation verified that 22% w/w was solubilised at an acidic pH (pH 2.0). The protein solubilisation increased with ionic strength, reaching 19.5% w/w in the highest NaCl concentration evaluated (200 mM). The particles were partially resistant to gastric conditions, with 30.5% w/w of total nitrogen protein solubilisation occurring after 2 h at pH 2.0; however, they did not resist the artificial intestine conditions, reaching 86.0% w/w of total nitrogen protein solubilisation after 5 h.
Keywords: Ionic gelation; alginate; electrostatic adsorption; layer-by-layer (LbL); whey proteins.