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Characterization of casein micelles and sodium caseinate in dense suspensions

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Author

  • Andrew Vasina

Summary, in English

This thesis describes the characterization of the rheological properties of dense suspensions of sodium caseinate and micellar casein with respect to changes in concentration (100-200g/L), pH (7.0-5.3), charge density (Δα), and temperature (5-40°C). The relationship between pH and charge density and how this relationship is affected by changes in temperature and concentration were also addressed. It has been shown that the pH of sodium caseinate and micellar casein suspensions is affected by concentration with the effect being stronger for dispersions of casein micelles. Changes in pH due to temperature were also observed for casein micelles dispersions, but not for those of sodium caseinate. The differences in the effects for sodium caseinate and casein micelles have been attributed to the presence of calcium phosphate. By measuring and comparing the changes in zero shear viscosity (h0) over the studied range of variables, new insights as to the dynamic interactions of sodium caseinate and casein micelles were observed. Both sodium caseinate and casein micelle suspensions demonstrate a sharp increase of viscosity as temperature is decreased or as the concentration is increased. When observing changes as a function of charge density or pH, sodium caseinate showed a progressive increase in h0, as the suspension was acidified toward the isoionic point, near which gelation occurs. When the Δα or pH was varied in casein micelles, gelation was observed as the suspension neared the isoionic point due to acidification, but also due to alkalinization. Between these critical gelation points, rheological behavior was observed to be dependent on both concentration and charge density due to counteracting interactions caused by changes in charge density and close packing.

Publishing year

2016

Language

English

Document type

Student publication for Master's degree (two years)

Topic

  • Agriculture and Food Sciences

Keywords

  • casein micelles
  • sodium caseinate
  • dense suspensions
  • charge density
  • rheology

Supervisor

  • Björn Bergenståhl (Professor)

ISBN/ISSN/Other

  • ISBN: 978-91-7623-892-9