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

Protein-polysaccharide conjugates often display improved techno-functional properties when compared to their individual involved biomolecules. alpha-Lactalbumin:acacia gum (alpha-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 alpha-la, alpha-la/AG mixtures and alpha-la:AG conjugates. Conjugate thermal stability was improved compared to pure alpha-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. alpha-la:AG conjugate solubility is affected in a complex manner by the three factors analyzed. Emulsifying activity index (EAI) of alpha-la is significantly affected by pH, while the alpha-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. (C) 2014 Elsevier Ltd. All rights reserved.