Demineralisation of whey by a combination of nanofiltration and anion‐exchange treatment: a preliminary study

Demineralisation is an important process for the utilisation of whey in the food industry. Sodium (Na+) and potassium (K+) ions pass through nanofiltration (NF) membranes in ion pairs with chloride (Cl−) to maintain electroneutrality, but NF processing can only partially remove these ions from whey, because the total Na and K content of whey generally exceeds the Cl content. In this work, a preliminary study of a new demineralisation method was made. A reconstituted sweet whey powder solution was first treated by Cl-form anion-exchange resin to increase the molar ratio of Cl to Na and K from ~0.5 to ~1.0. Subsequently, NF removed >90% of Na and K from the anion-exchange treated whey compared with <60% from the control whey. This new process could be useful for producing 70% demineralised whey with very low levels of the monovalent ions Na+, K+ and Cl−.