The mass transfer of sliced apple in aqueous mixtures of sucrose-whey protein concentrate (WPC) at 40°C was studied. WPC:Sucrose mixtures in different ratios and immersion times of up to 400 minutes were prepared. Water activity (a_w) was determined and osmotic pressure in aqueous solutions was calculated. The experimental data of mass loss (ML), water loss (WL) and solid gain (SG) of apple slices were determined. The apparent diffusion coefficients of water (D_w) were calculated. The results showed that the aw of the mixtures ranged from 0.947 to 0.998; whereas the average diffusion coefficients of water (D_w) varied from 1.16 to 2.32 x 10^-10 m²/s. It was observed that the lesser the quantity of sucrose and the bigger the WPC, mass loss in the equilibrium (ML_∞), water loss in the equilibrium (WL_∞) and Dw parameters decreased. When used 2:3 and 3:2 protein-sucrose solutions there was a flux resistance to mass, because it is likely to be formed a liquid membrane of biopolymer around the apple.