Acacia gum as modifier of thermal stability, solubility and emulsifying properties of α-lactalbumin

• Conjugates of α-lactalbumin:acacia gum (α-la:AG) were obtained by Maillard reaction.
• Decrease in free amino groups and coloring indicated reaction progress.
• Maillard Reaction modified the techno-functional properties of the α-la.
• Response surface methodology was successfully employed for optimization.

Protein–polysaccharide conjugates often display improved techno-functional properties when compared to their individual involved biomolecules. α-Lactalbumin:acacia gum (α-la:AG) conjugates were prepared via Maillard reaction by the dry-heating method. Conjugate formation was confirmed using results of absorbance, o-phthalaldehyde test, sodium dodecyl sulfate–polyacrilamide gel electrophoresis (SDS–PAGE) and size exclusion chromatography. Techno-functional properties (emulsifying characteristics, solubility, and thermal stability) were evaluated for α-la, α-la/AG mixtures and α-la:AG conjugates. Conjugate thermal stability was improved compared to pure α-la treated at the same conditions of conjugate formation. Response surface methodology was used to establish models to predict solubility and emulsifying activity as functions of the salt concentration, pH and reaction time. α-la:AG conjugate solubility is affected in a complex manner by the three factors analyzed. Emulsifying activity index (EAI) of α-la is significantly affected by pH, while the α-la:AG EAI is affected by the three analyzed factors. Both solubility and EAI are maximized with pH 8.0, NaCl concentration of 0.3 mol L−1 and two days of Maillard reaction.