Emulsifying Properties of Angum Gum (Amygdalus scoparia Spach) Conjugated to β-Lactoglobulin through Maillard-Type Reaction

In this study, emulsifying properties of Angum gum were improved by covalent bonding with β-lactoglobulin (BLG). Angum gum is a natural gum exudate from mountain almond trees (Amygdalus scoparia Spach). Covalent linkage of β-lactoglobulin-Angum gum conjugate was confirmed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Emulsifying properties of emulsions containing β-lactoglobulin:Angum gum (1:1) conjugates were studied with the advancement of Maillard reaction. Dry-heating time showed no significant (p > 0.05) effect on the emulsion activity index; however, emulsion stability index were significantly increased over time and emulsion stability index of two weeks incubated β-lactoglobulin-Angum gum conjugate was significantly different (p < 0.05) from others (β-lactoglobulin-Angum gum mixture, 0, 2, 6 days, and 2 weeks). Moreover, the creaming index decreased with advancement of Maillard-type conjugation of β-lactoglobulin:Angum gum (1:1). β-lactoglobulin-Angum gum conjugates (1:1, 1:2, and 2:1) exhibited much better emulsification performance than Angum gum and gum Arabic alone at the same emulsifier/oil ratio (1.5 wt. % total biopolymer/ 40% v/v oil). In addition, assessing droplet size distribution during storage and freeze-thaw treatment revealed that β-lactoglobulin:Angum gum (1:1) conjugate had finer droplet size compared to other β-lactoglobulin/Angum gum mixing ratios (1:2 and 2:1), Angum gum and gum Arabic.