Agradecimentos: María L. Herrera and Roberto J. Candal are researchers of the National Research Council of Argentina (CONICET). This work was supported by CONICET through Project PIP 11220110101025, the National Agency for the Promotion of Science and Technology (ANPCyT) through Project PICT 2013-0897, and by the University of Buenos Aires through Project UBA-20020130100136BA. Iris L. Torriani is a I-B researcher of the Brazilian National Research Council (CNPq). CLPO was supported by FAPESP (Proj. # 2010/09277-7) and CNPq. The authors wish to thank the Synchrotron Light National Laboratory (LNLS, Campinas, Brazil) for the use of the SAXS facilities through project D11A-SAXS1-14296 Ver menos

Abstract: Flocculation process was studied in emulsions formulated with 10 wt.% sunflower oil, 2, 5 or 7.5 wt.% NaCas, and with or without addition of sucrose (0, 5, 10, 15, 20 or 30 wt.%). Two different processing conditions were used to prepare emulsions: ultraturrax homogenization or further homogenization by ultrasound. Emulsions with droplets with diameters above (coarse) or below (fine) 1 pm were obtained. Emulsions were analyzed for droplet size distribution by static light scattering (SLS), stability by Turbiscan, and structure by confocal laser scanning microscopy (CLSM) and small angle X-ray scattering (SAXS). SAXS data were fitted by a theoretical model that considered a system composed of poly dispersed spheres with repulsive interaction and presence of aggregates. Flocculation behavior was caused by the self-assembly properties of NaCas, but the process was more closely related to interfacial protein content than micelles concentration in the aqueous phase. The results indicated that casein aggregation was strongly affected by disaccharide addition, hydrophobic interaction of the emulsion droplets, and interactions among interfacial protein molecules. The structural changes detected in the protein micelles in different environments allowed understanding the macroscopic physical behavior observed in concentrated NaCas emulsions Ver menos