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 W1/O/W2 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 (W2) phase, respectively. The stability and encapsulation efficiency of the W1/O/W2 emulsions depended on the ratio of W1/O emulsion to W2 phase, as well as the concentration of GA and XA within the outer W2 phase. A W1/O/W2 emulsion prepared using 2 % (w/w) GA and 0.3 % (w/w) XA in the W2 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 W1 to W2 phases increased, which can be attributed to increasing solubility in the oil phase. The encapsulation efficiency of lysine encapsulated in GA-XA-stabilized W1/O/W2 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.