The effect of calcium removal from milk on casein micelle stability and structure

The total calcium level of raw skimmed milk was reduced by 10, 19, 29, 40 and 51% using Duolite® ion-exchange resin. The products were examined for concentrations of ionic calcium, sodium and potassium and the pH, ethanol stability, micelle diameter and ζ-potential were also measured. Ionic calcium decreased with removal of calcium and pH increased. Calcium removal resulted in an increase in the ethanol stability from 88% to above 100%. Casein micelle diameter increased as calcium was removed. The ζ-potential of the skimmed bulk milk was -24.4 mV, gradually becoming more negative with calcium removal to -30.6 mV after 51% calcium removal. The milk became more translucent as calcium was removed. To investigate the reversibility of this process, calcium chloride was added back to the depleted samples to restore their original total calcium content. At 51% removal, restoration of the total calcium level resulted in formation of clots. At levels of 10 and 19% calcium removal, the ethanol stability remained above 100%, but at higher levels of calcium removal the alcohol stability was adversely affected when the calcium was added back. Adding back calcium resulted in partial restoration of the original casein micelle diameter.

The Good Shepherd

Solo show.

The universal addressability of dumb things

Group exhibition curated by Mark Leckey.

The hecklers

Group Exhibition curated by Cedar Lewisohn. Contributors: Caroline Achaintre, Edwin Burdis, Slawomir Czajkowski (Zbiok), Shaun Doyle and Mally Mallinson, Ruth Ewan, Andrew Gilbert, Joel Gray, Tod Hanson, Geoffrey Ireland, kennardphillipps, Cedar Lewisohn (curator), Kieron Livingstone and Ian Allison, Alexis Milne, Laura Oldfield Ford, Max Reeves, Clunie Reid, John Russell, Francis Thorburn, Vicky Wright.