dynamic light scattering the method and some applications

#Dynamic light scattering the method and some applications free

Casein micelles were characterised before and after HPP using Dynamic Light Scattering (DLS) and Small Angle X-ray Scattering (SAXS). This allows experiments to be performed to determination the effect of whey protein on CM under a range of conditions. SCM were successfully formed in this work by the controlled, slow pumping of casein, Ca 2+, phosphate, and citrate solutions into a mixing vessel at 37 ☌. This difference influences subsequent phase transformations. The precipitate formed in these nucleation experiments was shown to be a more stable DCPD phase compared to an amorphous phase formed during rapid mixing of Ca 2+ and phosphate.

#Dynamic light scattering the method and some applications free

This suggests that calcium phosphate followed a classical nucleation model in contrast to the calcium carbonate system where a novel thermodynamic equilibrium model was recently proposed based on the linearity of the free Ca 2+ versus total added Ca 2+ line. The slope of the free Ca 2+ versus total added Ca 2+ line decreased over time prior to calcium phosphate precipitation. A calcium ion selective electrode was used to monitor free Ca 2+ during the pre-nucleation stage as CaCl2 was slowly added to a phosphate solution. The second objective of this work was to determine the effect of whey protein on synthetic casein micelles (SCMs) before and following HPP. It is known that HPP can denature whey protein and this has been proposed as the cause of irreversible changes to the CM structure following HPP. The objective of this work was to investigate the pre-nucleation stage of calcium phosphate followed by its transformation in inorganic system. In addition, colloidal calcium phosphate is a metastable phase and calcium phosphate transformations from more soluble to less soluble forms can be important in milk systems and influences the stability of milks, particularly the CM. Calcium phosphate is abundant in nature and its pre-nucleation chemistry was investigated in this work following the recent proposal of a novel pre-nucleation process in calcium carbonate systems.

This thesis presents a study on two aspects of CM stability the first is on the inorganic calcium phosphate particles and the second is on the influence of whey proteins on CM chemistry following high pressure processing (HPP).

Milk is a complex system and its structure and properties are greatly influenced by the interaction between colloidal calcium phosphate and casein in the form of casein micelles (CM).