Effects of high pressure and heat treatment on the mineral balance of goats' milk

Changes in the distribution of minerals in skim goats' milk by high pressure (400 MPa) and/or heat (85 degrees C for 30 min) treatment have been studied. Heat treatment caused reduced solubility of the calcium, magnesium and phosphorus, and this increased with the severity of heating. In contrast, high pressure released different levels of micellar elements into the soluble phase without causing appreciable changes in pH or ionic calcium concentration. The levels of soluble salts returned to their original values when the heated samples were subjected to high pressure. However, heating pressurized milk resulted in concentrations of soluble minerals that were lower than in control milks, and close to values found in heated milks. The salt balance in goats' milk was less affected by high pressure treatment at 75 degrees C than was that of cows' milk. These results are discussed in relation to the effects of high pressure and heat treatment on mineral equilibrium and micellar structure.