Osmotic drying

Van Nieuwenhuijzen, N.H., Zareifard, M.R., and Ramaswamy, H.S. 2001. Osmotic drying kinetics of cylindrical apple slices of different sizes. Dry. Technol. 19, 525-545. 

Other applications of liquid-solid fluidized beds that have been suggested or put into practice include the leaching of vegetable oils from seeds (Epsfein, 2003), fhe freeze concentration of solutions (Rios et al., 1985) and osmotic drying (Marouze et al., 2001). Fluidization is also the basis of fhe hydraulic fransport of vegetables (McKay et al., 1987). Three-phase fluidized beds have been employed for the fermentation of cocoa beans (Jacquef et al, 1981 Rios et al, 1985). 

Moreno, M. C. and Bouchon, P. (2008). A different perspective to study the effect of freeze, air, and osmotic drying on oil absorption during potato frying. ]. Food Sci. 73, E122-E128. 

H. Sarosi and A. Polak, Possibilities of application of osmotic drying in the food industry, Tudomanyos Kozlemenyck Elelmiszeripari Foiskola, 6 63 (1976). 

Microreticular Resins. Microreticular resins, by contrast, are elastic gels that, in the dry state, avidly absorb water and other polar solvents in which they are immersed. While taking up solvent, the gel structure expands until the retractile stresses of the distended polymer network balance the osmotic effect. In nonpolar solvents, little or no swelling occurs and diffusion is impaired. 

Ultrafiltration. Membranes are used that are capable of selectively passing large molecules (>500 daltons). Pressures of 0.1—1.4 MPa (<200 psi) are exerted over the solution to overcome the osmotic pressure, while providing an adequate dow through the membrane for use. Ultrafiltration (qv) has been particulady successhil for the separation of whey from cheese. It separates protein from lactose and mineral salts, protein being the concentrate. Ultrafiltration is also used to obtain a protein-rich concentrate of skimmed milk from which cheese is made. The whey protein obtained by ultrafiltration is 50—80% protein which can be spray dried. 

Salt preserves foods by providing a hostile environment for certain microorganisms. Within foods, salt brine dehydrates bacterial cells, alters osmotic pressure, and inhibits bacterial growth and subsequent spoilage. Dry salt and salt brine are used in several types of curing processes. Pickles are preserved in strong brine before final processing. 

Growth characteristics of cells exposed to water stress mimic some of the structural responses of organised plant tissues. A frequently observed response of plants exposed to water stress is a reduction in cell size (Cutler, Rains Loomis, 1977). This cellular phenomenon was observed in tomato cells stressed with PEG (Handa et al., 1983). Concomitantly with a decrease in cell size with increasing osmotic stress was a reduction in fresh weight. In contrast the dry weight was not affected. 

The membrane is critically important in osomometry. Selection of a membrane involves reconciliation of high permeability toward the solvent with virtual impermeability to the smallest polymer molecules present in the sample. Membranes of cellulose are most widely used. Commercially Regenerated cellulose film is a common source. The undried gel cellophane film is often preferred, but the dry film may be swollen in water (or in aqueous solutions of caustic or zinc chloride ) to satisfactory porosity. Useful cellulose membranes may also be prepared by denitration of nitrocellulose films/ and special advantages have been claimed for bacterial cellulose films. The water in the swollen membrane in any case may be replaced by a succession of miscible organic solvents ending with the one in which osmotic measurements are to be made. Membranes of varying porosity may be... 

TBW depletion (often referred to as dehydration ) is typically a more gradual, chronic problem compared to ECF depletion. Because TBW depletion represents a loss of hypotonic fluid (proportionally more water is lost than sodium) from all body compartments, a primary disturbance of osmolality is usually seen. The signs and symptoms of TBW depletion include CNS disturbances (mental status changes, seizures, and coma), excessive thirst, dry mucous membranes, decreased skin turgor, elevated serum sodium, increased plasma osmolality, concentrated urine, and acute weight loss. Common causes of TBW depletion include insufficient oral intake, excessive insensible losses, diabetes insipidus, excessive osmotic diuresis, and impaired renal concentrating mechanisms. Long-term care residents are frequently admitted to the acute care hospital with TBW depletion secondary to lack of adequate oral intake, often with concurrent excessive insensible losses. 

---