INVESTIGADORES
HERRERA Maria Lidia
congresos y reuniones científicas
Título:
Stability and Structure of Sodium Caseinate Emulsions
Autor/es:
M. L. HERRERA; C. HUCK IRIART; R. J. CANDAL
Lugar:
Campinas
Reunión:
Congreso; 21ra Reunión Annual de Usuarios del LNLS; 2011
Institución organizadora:
Laboratorio Nacional de Luz Sincrotrón
Resumen:
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.