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Published on: January 12, 2009
Caseins are cross-linked through their ester phosphate groups by colloidal calcium phosphate.
Biochimica Et Biophysica Acta
|January 30, 1987
Summary
Artificial casein micelles are formed by cross-linking casein proteins with colloidal calcium phosphate. This cross-linking primarily involves ester phosphate groups on specific casein types, influencing micelle structure and composition.
Area of Science:
- Food Science
- Biochemistry
- Colloid Science
Background:
- Casein micelles are complex colloidal structures essential in milk.
- Understanding the cross-linking mechanisms within casein micelles is crucial for dairy science and food technology.
Purpose of the Study:
- To investigate the role of colloidal calcium phosphate in cross-linking casein proteins within artificial casein micelles.
- To determine the specific casein fractions involved in colloidal calcium phosphate cross-linking and their composition.
Main Methods:
- Preparation of artificial casein micelles using sodium caseinate, calcium, phosphate, and citrate.
- Quantification of casein aggregates using high-performance gel chromatography (HPGPC) with 6 M urea.
- Analysis of casein composition in aggregates via high-performance ion-exchange chromatography (HPIEC).
Main Results:
- Approximately 48% of total casein in artificial micelles formed aggregates cross-linked by colloidal calcium phosphate.
- Alpha s1-casein (53.1%), beta-casein (31.1%), and alpha s2-casein (15.8%) were identified as the primary cross-linked fractions.
- Cross-linking correlated with the ester phosphate content of casein constituents; kappa- and gamma-caseins were not cross-linked unless chemically phosphorylated.
Conclusions:
- Caseins are cross-linked by colloidal calcium phosphate through their ester phosphate groups.
- The degree of cross-linking varies among casein types, with alpha s1-casein being most susceptible.
- Phosphorylation status is critical for casein susceptibility to colloidal calcium phosphate-induced cross-linking.
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