ABSTRACT
Osmotic dehydration is a process of partial removal of water from plant tissues by immersion in a concentrated solution of sugar or salt. Due to the difference in osmotic pressure between the food and the solution, water is transported from the
material into the solution. The diffusion of water is accompanied by the simultaneous counterdiffusion of solute from the osmotic solution into the tissue. Since the membrane responsible for osmotic transport is not perfectly selective, other solutes present in the cells can also be leached into the osmotic solution (Dixon and Jen, 1977; Lerici et al., 1985; Giangiacomo et al., 1987). The rate of diffusion of water from any material made up of such tissues depends upon factors such as:
• The temperature and concentration of the osmotic solution • The size and geometry of the material • The solution to material mass ratio • The level of agitation of the solution
A number of recent publications have described the influence of these variables on mass transfer rates during osmotic dehydration (Roult-Wack et al., 1992; Torreggiani, 1993; Roult-Wack, 1994; Rastogi and Raghavarao, 1994, 1995, and 1997a and b; Rastogi et al., 1997).
