INSTITUTO DE QUIMICA, FISICA DE LOS MATERIALES, MEDIOAMBIENTE Y ENERGIA
Unidad Ejecutora - UE
congresos y reuniones científicas
Stability and Structure of Sodium Caseinate Emulsions
M. L. HERRERA; C. HUCK IRIART; R. J. CANDAL
Congreso; 21ra Reunión Annual de Usuarios del LNLS; 2011
Laboratorio Nacional de Luz Sincrotrón
Most dispersed multiphase systems are thermodynamically unstable per se and thus require stabilization. In the food industry, actually stabilization of emulsions is obtained by the addition of proteins. Sodium caseinate is widely used as an ingredient due to its functional properties, which include emulsification, water and fat-binding, thickening and gelation. The aim of the present work was to investigate the effect of sodium caseinate or sugar concentrations and fat phase composition on the stability and structure of emulsions formulated with a concentrated from fish oils, sunflower or olive oils as fat phase. The main mechanism of destabilization in a given formulation depended on NaCas concentration. Emulsions formulated with 0.5 and 1 wt.% NaCas destabilized mainly by creaming. For the 2 wt.% NaCas emulsion, both creaming and flocculation mechanisms, were involved while for emulsions stabilized by 3, 4 or 5 wt.% NaCas the main mechanism was flocculation. When trehalose was added to emulsions, the rate of destabilization was markedly lower. The 5 wt.% NaCas emulsion did not flocculate during a week at 22.5°C. Its back scattering remained unchanged during storage showing a great stability. This sample remained fully turbid and in the liquid state. SAXS patterns for emulsions formulated with 0, 20 or 30 wt.% trehalose, 10 wt.% CFO and 5 wt.% NaCas were analyzed at 8°C. As was expected addition of sugar diminished the intensity of the signal since electron density of aqueous trehalose solutions increased with concentration and therefore there was less contrast. Values of q were 0.241, 0.248, and 0.252 nm_1 for emulsions with 0, 20, and 30 wt.% trehalose, respectively. Some aqueous phase components such as hydrocolloids proved to stabilize emulsions because they increase viscosity. The slightly increased of q values with trehalose addition might suggest that trehalose had an effect further than viscosity changes since the aggregation state of the protein changed with the aqueous phase formulation. These results were in agreement with the small particle size found when trehalose was added to aqueous phase. Changes in fat phase did not affect q values. However, patterns had different intensities and shapes. A deeper analysis of the scattering curves would provide more information about the internal organization of casein micelles.