High pressure-induced changes in ovine milk. 1. Effects on the mineral balance and pH

In this study, the effects of high pressure (HP) treatment on the mineral balance and pH of raw skimmed ovine milk were examined. HP treatment increased the level of non-sedimentable calcium and phosphate in ovine milk; such increases are probably the result of HP-induced solubilisation of micellar calcium phosphate. The HP-induced increases in the levels of non-sedimentable calcium and phosphorus were reversible on subsequent storage both at 5 and 20°C for 4 or 24 h. As a result of HP-induced solubilisation of micellar calcium phosphate, an HP-induced increase in milk pH was observed, which was reversible on subsequent storage at 20°C, but remained largely irreversible at 5°C. HP treatment affected the mineral balance and pH of ovine milk in a manner analogous to that observed in bovine, buffalo and caprine milk, although there were considerable inter-species differences in the pressure at which specific effects occurred.