Encapsulation of amino acids in water-in-oil-in-water emulsions stabilized by gum arabic and xanthan gum.

In this study, several kinds of amino acids were successfully encapsulated in a W/O/W emulsion produced using a two-step emulsification process. Polyglycerol polyricinoleate (PGPR) was used as a hydrophobic emulsifier in the oil phase, while gum arabic (GA) and xanthan gum (XA) were used as an emulsifier and stabilizer in the outer water (W) phase, respectively. The stability and encapsulation efficiency of the W/O/W emulsions depended on the ratio of W/O emulsion to W phase, as well as the concentration of GA and XA within the outer W phase. A W/O/W emulsion prepared using 2 % (w/w) GA and 0.3 % (w/w) XA in the W phase exhibited good stability and a high encapsulation efficiency (>80 %) for several amino acids. As the hydrophobicity of amino acids and storage temperature increased, the leakage from the W to W phases increased, which can be attributed to increasing solubility in the oil phase. The encapsulation efficiency of lysine encapsulated in GA-XA-stabilized W/O/W double emulsion was over 84 % after 28 days storage at 4 °C. These results indicate that double emulsions may be useful for the encapsulation of amino acids, which may be useful to protect them from their environment and mask bitter flavors.