title: Solvent-mediated disruption of bovine casein micelles at alkaline pH.
abstract: The disruption of casein micelles at alkaline pH was investigated using turbidity measurements. The rate and extent of disruption of casein micelles at alkaline pH (8.0-11.0) increased with pH. Furthermore, the extent of alkaline disruption increased with increasing temperature (5-40 degrees C). Preheating milk for 10 min at 90 degrees C did not influence the extent of alkaline disruption of casein micelles, suggesting that whey proteins do not influence the alkaline disruption process. Levels of ionic calcium and serum calcium and phosphate decreased in a logarithmic fashion with increasing pH, indicating precipitation of calcium phosphate onto the casein micelles. A mechanism for alkaline disruption of casein micelles is proposed, in which increasing the milk pH improves the solvent quality for the caseins, thereby leading to the disruption of casein micelles into their constituent nanoclusters; increases in the net-negative charge on the caseins on increasing pH may contribute to micellar dissociation.
authors.affiliation: Department of Food and Nutritional Sciences, University College Cork, Cork, Ireland.
authors.forename: Betsy
authors.initials: B
authors.lastname: Vaia
authors.forename: Mary A
authors.initials: MA
authors.lastname: Smiddy
authors.forename: Alan L
authors.initials: AL
authors.lastname: Kelly
authors.forename: Thom
authors.initials: T
authors.lastname: Huppertz
mesh_terms: D000818:Animals; D002130:Calcium Phosphates / Q000737:chemistry; D002364:Caseins / Q000737:chemistry*; D002417:Cattle; D011232:Chemical Precipitation; D006863:Hydrogen-Ion Concentration; D008823:Micelles; D008892:Milk / Q000737:chemistry; D009391:Nephelometry and Turbidimetry; D012997:Solvents
chemical_list: D002130:Calcium Phosphates; D002364:Caseins; D008823:Micelles; D012997:Solvents; C020243:calcium phosphate