Solutions of whey protein and lactose were mixed at the following whey protein/lactose proportions by weight: 0.01/99.99, 0.1/99.9, 1/99, 5/95, 20/S0 and 40/60. To avoid precipitation of the protein, the pH of the lactose solution was raised to 7 before mixing with the protein solution. The dry weight in all solutions was 10% (by weight).