Composition and interfacial properties of casein micelle fractions

Publisher Website
Google Scholar
Abstract
Summary: Casein micelles in a reconstituted bovine skim milk were dissociated by dialysing them against various concentrations of EDTA. Gel chromatography showed a gradual but limited dissociation when micellar Ca was chelated and two main fractions were isolated. Monolayer technique and gel electrophoresis were used to characterize the interfacial properties and composition of the fractions. The first fraction contained highly cohesive complexes that did not unfold at the air-water interface. From π-A isotherms the close-packing area (A0) was 0·08 m2 mg-1 and was related to an average particle diameter of 9·1 nm. κ-Casein was concentrated in this fraction in an equimolar ratio with β-caseins and a variable ratio with αs-casein (0·55–1·10). These particles are thought to represent submicelles. The complexes of the second fraction were easily disrupted and spread out at the interface like casein monomers, with a close-packing area of 1·05 m2 mg-1. Two different complexes were identified in this last fraction. One of them contained an approximately equimolar ratio of αs- and β-caseins, and the other was composed exclusively of αs-casein. The results are discussed in relation to casein interactions leading to micelle formation.

This publication has 29 references indexed in Scilit: