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Partitioning of calcium in human milk after freezing and thawing

Partitioning of calcium in human milk after freezing and thawing Minimal calcium in fresh human milk occurs in the fat. Freshly-collected milk was partitioned into fat and skim milk fractions, and the skim milk was partitioned into a colloidal fraction containing casein micelles, and a diffusible fraction. This fractionation was repeated after freezing and thawing three times over 14 days. Up to 51% of the total calcium was found in the fat layer of the milk after sequential freezing and thawing. We aimed to contribute to the understanding of the calcium interactions that cause this redistribution. Freezing and thawing disrupts the fat globule membrane and releases fatty acids. We calculated that the amount of fatty acids generated by freezing and thawing of the milk would bind only a minor proportion of the calcium that was transferred to the fat layer. In addition, the calcium that appeared in the fat layer was not removed from the colloidal fraction and therefore there was no evidence of disruption of the casein micelles. This suggests that the majority of the calcium that appears in the fat of human milk after freezing and thawing can be attributed to increases in the binding of calcium to the fat globule membranes. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Dairy Science & Technology Springer Journals

Partitioning of calcium in human milk after freezing and thawing

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Publisher
Springer Journals
Copyright
Copyright © 2009 by Springer S+B Media B.V.
Subject
Chemistry; Food Science; Agriculture; Microbiology
ISSN
1958-5586
eISSN
1958-5594
DOI
10.1051/dst/2008035
Publisher site
See Article on Publisher Site

Abstract

Minimal calcium in fresh human milk occurs in the fat. Freshly-collected milk was partitioned into fat and skim milk fractions, and the skim milk was partitioned into a colloidal fraction containing casein micelles, and a diffusible fraction. This fractionation was repeated after freezing and thawing three times over 14 days. Up to 51% of the total calcium was found in the fat layer of the milk after sequential freezing and thawing. We aimed to contribute to the understanding of the calcium interactions that cause this redistribution. Freezing and thawing disrupts the fat globule membrane and releases fatty acids. We calculated that the amount of fatty acids generated by freezing and thawing of the milk would bind only a minor proportion of the calcium that was transferred to the fat layer. In addition, the calcium that appeared in the fat layer was not removed from the colloidal fraction and therefore there was no evidence of disruption of the casein micelles. This suggests that the majority of the calcium that appears in the fat of human milk after freezing and thawing can be attributed to increases in the binding of calcium to the fat globule membranes.

Journal

Dairy Science & TechnologySpringer Journals

Published: May 21, 2011

References