Apples (Fuji variety) were treated in aqueous sucrose (50% w/w) and salt (NaCl, 10% w/w) solutions for 2,
4 and 8 h (27 C). Concentration profiles were determined as a function of the distance, considering the
unidirectional and normal diffusion to the exposed face of the immersed fruit. The density, water, sugar
and salt contents were determined for each piece of apple. A mathematical model was fitted to the experimental
data for the water, sucrose and salt contents. A numerical method of finite differences allowed for
the calculation of the effective diffusion coefficients as a function of concentration, using the material
coordinates to consider tissue shrinkage. The coefficients were obtained by simultaneously integrating
the three differential equations (for water, sucrose and salt). The behavior of the apple cellular tissue
was also studied using light microscopy techniques to obtain images of the osmotically treated pieces.