Abstract
The association of calcium with major whey protein fractions, α-lactalbumin and β-lactoglobulin, was studied in model solutions between pH 3.5 and 7.0 and ionic strength ranging from 0.04 to 0.16M. Both α-lactalbumin and β-lactoglobulin showed capability to associate with calcium. However, the extent of association was markedly pH dependent. Below pH 4.0 interactions between calcium and α-lactalbumin were insignificant. The amount of calcium attached to this protein increased at pH values approaching neutrality. The overall calcium-associating capability of β-lactoglobulin was about half of that of α-lactalbumin. The first signs of a calcium-β-lactoglobulin interaction were observed above pH 5.0. The increase of ionic strength had a negative effect on calcium association with both whey protein fractions. The calcium binding data from simple buffer solutions were confirmed in a model whey system. Whey protein-calcium interactions in cheese wheys appear to follow three distinctive patterns: no such interactions below pH 4.0; limited interactions between pH 4.0 and 5.5 due only to α-lactalbumin; and significant interactions above pH 5.5 due to both α-lactalbumin and β-lactoglobulin.
Published Version
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