Measurement of ionic calcium in milk

Lin, M.J., Lewis, M.J. and Grandison, A.S. (2006) Measurement of ionic calcium in milk. International Journal of Dairy Technology, 59 (3). pp. 192-199. ISSN 1364-727X doi: 10.1111/j.1471-0307.2006.00263.x

Abstract/Summary

There are many reports in the literature regarding the effects of ionic calcium on reactions related to casein micelle stability, such as heat stability, ethanol stability and susceptibility to gelation, sediment formation and fouling. However, experimental evidence supporting these assertions is much less readily available. This paper evaluates three selective ion electrode systems for measuring ionic calcium directly in milk as well as looking at the effects on pH reduction and addition of calcium chloride. The best electrode system was the Ciba Corning 634 system, which was designed for blood but has been modified for milk. This was found to be reproducible and stable when calibrated daily and allowed direct measurements to be taken on milk in 70 s. This has been found to perform well now for 3 years. The other systems were not so useful, as they took longer to stabilize, but may be useful for higher ionic calcium concentrations, which are found in acidified milk products. Reducing the pH increased ionic calcium and reduced ethanol stability. Calcium chloride addition reduced pH, increased ionic calcium and reduced the ethanol stability. Readjusting the pH to its value before calcium addition reduced the ionic calcium, but not back to its original value. Milks from individual cows showed wide variations in their ionic calcium concentrations. This establishes the methodology for a more detailed investigation on measurement of ionic calcium in milks from individual cows and from bulk milks, to allow a better understanding of its role in casein micelle stability.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/13201
Item Type	Article
Refereed	Yes
Divisions	Life Sciences > School of Chemistry, Food and Pharmacy > Department of Food and Nutritional Sciences
Uncontrolled Keywords	calcium supplementation, ethanol stability, ionic calcium, HEAT-STABILITY, INORGANIC CONSTITUENTS, CASEIN MICELLES, PHOSPHATE, PH
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