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Small-angle X-ray scattering investigation of the micellar and submicellar forms of bovine casein

Published online by Cambridge University Press:  01 June 2009

Helmut Pessen ,
Thomas F. Kumosinski  and
Harold M. Farrell Jr
Helmut Pessen
Affiliation:
Eastern Regional Research Center, U.S. Department of Agriculture, 600 E. Mermaid Lane, Philadelphia, Pennsylvania 19118, U.S.A.
Thomas F. Kumosinski
Affiliation:
Eastern Regional Research Center, U.S. Department of Agriculture, 600 E. Mermaid Lane, Philadelphia, Pennsylvania 19118, U.S.A.
Harold M. Farrell Jr
Affiliation:
Eastern Regional Research Center, U.S. Department of Agriculture, 600 E. Mermaid Lane, Philadelphia, Pennsylvania 19118, U.S.A.
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Summary

Small-angle X-ray scattering was performed on whole casein under submicellar (Ca2+ removed) and micellar (Ca2+ re-added) conditions. Submicellar scattering curves showed two Gaussian components which were interpreted in terms of a spherical particle with two concentric regions of different electron density, a relatively compact core of higher electron density and a looser shell. Normalized scattering curves and calculated distance distribution functions were consistent with this picture. Micellar scattering data, which can yield only cross-sectional information related to a window of scattered intensities, could be analysed by a sum of three Gaussians with no residual function. The two Gaussians with the lower radii of gyration were again taken to indicate the two concentric regions of different electron density of inhomogeneous spherical particles; the third Gaussian was shown to reflect the packing number of these particles within a cross-sectional portion of the micelle, which was 3:1 for this system. These results are a strong indication that submicellar inhomogeneous particles containing hydrophobically stabilized inner cores exist within the colloidal micelle.

Type
Original Articles
Information
Journal of Dairy Research , Volume 56 , Issue 3: Special Issue: Proceedings of the Hannah Research Institute Casein Conference , May 1989 , pp. 443 - 451
Copyright
Copyright © Proprietors of Journal of Dairy Research 1989

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References

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