Effects of the Mode of the Filtration Processes on the Fractionation of Milk Constituents by Ultrafiltration

Abstract

1. In fractionation of cow's milk costituents by ultrafiltration with the module UFP-10 of Rhone-Poulenc-Chimie Fine, theoretical analyses were attempted by means of the theoretical equations which were derived in the previous article in order to study the effects of pH, temperature, pre-heating and fat content of milk and the membrane varieties (IRIS 3038 and IRIS 3072). The theoretical analyses tested here were capable to be applied to the all experimental conditions of the present ultra filtration, 2. Permeability coefficient and membrane-permeable fraction of each milk constituent varied as a function of its physico-chemical characteristics within the range of the present experimental conditions. However, the performances of calcium, magnesium and phosphorus, which form colloids in milk, were exclusively dependent upon the filtration conditions. 3. Permeability coefficients of permeable milk solids, protein and lactose were affected solely by the properties of membrane. Permeability coefficients of potassium, calcium, magnesium and phosphorus were higher in the cases of the membrane vaiety of IRIS 3072, whole milk and at 10°C to 15°C than in those cases of IRIS 3038, skim milk and at 50°C. The values of permeability coefficients of sodium and chlorine were lower at pH 5. 8 than at pH 6. 7, while those values of potassium, calcium, magnesium and phosphorus were higher at pH 5. 8 than at pH 6. 7. Permeability coefficient of chlorine was insusceptible to the filtration coditions other than pH and also displayed very limited correlation with permeability coefficients of other 5 mineral components. 4. Membrane-permeable fractions of protein, fat, lactose, sodium, potassium and chlorine were less influenced by the changes of filtration conditions. Membranepermeable fractions of calcium, phosphorus and ash were intensely correlated mutually, and increased or decreased when pH was lowered or the temperature was elevated, respectively. Molar ratio of calcium to phosphorus in colloidal calcium phosphate complexes, transiting between the permeable and non-permeable phase in accordance with the changes of filtration conditions, was 1. 52 which was comparable with that of tri-calcium phosphate.