Distribution of minerals between the soluble and colloidal phases in commercial UHT milks

Forty-one UHT commercial whole and skim milks were analysed to determine th e total and soluble content of mineral (calcium, phosphorus and magnesium), Ionic calcium and lactulose were also examined. UHT treatment of raw milk samples with added polyphosphate or permeate were also carried out in order to evaluate the effects on the salt balance. Lactulose concentrations in c ommercial samples ranged from 154 to 1372 mg/l and no correlation could be established with the soluble mineral content. Samples showed wide intervals of variation in the mineral distribution. The reasons of this variability could be attributed to different causes: nature of the samples, processing conditions or addition of permitted polyphosphates. Addition of polyphospha tes to raw milk caused a decrease in soluble calcium and magnesium in UHT t reated samples whereas the soluble phosphorus increased. The addition of sk im milk permeate to raw milk prior to UHT treatment did not cause appreciab le variations in the soluble mineral content.