Résumé
Main goal of this research was to examine the emulsifying properties of acid and sweet wheys extracted from bovine and camel fresh milks after heating at 70 and 90 °C for 30 min at laboratory scale. Specifically, emulsifying properties (emulsification stability (ESI) and activity (EAI) indexes) and the physico-chemical characteristics (surface hydrophobicity, ζ-potential, interfacial tension and denaturation rate) of wheys were assessed. Maximum EAI and ESI were found for sweet wheys (EAI~ 2 m2/g; ESI~ 65%), with higher EAI values for the camel whey. This behavior was explained by the strongest electrostatic-repulsive forces between oil droplets under conditions away from the isoelectric-point of proteins in agreement with the ζ-potential measurements.Findings indicate that heating affected the physico-chemical properties of camel and bovine whey proteins in acidic conditions by increasing surface hydrophobicity and the ability to reduce the interfacial tension. These results confirmed the protein-protein aggregation of heated acid wheys as proved by electrophoreses.