Measurement of ionic calcium, pH and soluble divalent cations in milk at high temperature

On-Nom , N., Grandison, A. S. and Lewis, M. J. (2010) Measurement of ionic calcium, pH and soluble divalent cations in milk at high temperature. Journal of Dairy Science, 93 (2). pp. 515-523. ISSN 0022-0302 doi: 10.3168/jds.2009-2634

Abstract/Summary

Dialysis and ultrafiltration were investigated as methods for measuring pH and ionic calcium and partitioning of divalent cations of milk at high temperatures. It was found that ionic calcium, pH, and total soluble divalent cations decreased as temperature increased between 20 and 80°C in both dialysates and ultrafiltration permeates. Between 90 and 110°C, ionic calcium and pH in dialysates continued to decrease as temperature increased, and the relationship between ionic calcium and temperature was linear. The permeabilities of hydrogen and calcium ions through the dialysis tubing were not changed after the tubing was sterilized for 1h at 120°C. There were no significant differences in pH and ionic calcium between dialysates from raw milk and those from a range of heat-treated milks. The effects of calcium chloride addition on pH and ionic calcium were measured in milk at 20°C and in dialysates collected at 110°C. Heat coagulation at 110°C occurred with addition of calcium chloride at 5.4mM, where pH and ionic calcium of the dialysate were 6.00 and 0.43mM, respectively. Corresponding values at 20°C were pH 6.66 and 2.10mM.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/8163
Item Type	Article
Refereed	Yes
Divisions	Life Sciences > School of Chemistry, Food and Pharmacy > Department of Food and Nutritional Sciences > Food Research Group
Uncontrolled Keywords	pH, ionic calcium, dialysis, ultrafiltration
Publisher	American Dairy Science Association
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