Sucrose, equilibrium water content

Figure 21.13 Equilibrium water content of fructose and sucrose/...

The stoppers for vials contain a certain amount of water, which depends on the composition of the stoppers. De Grazio and Flynn [1.86] showed, that the selection of the polymer, the additives for the vulcanization, and the filler influence the adsorption and desorption of water. However even the best possible mixture increases the RM in 215 mg sucrose from 1.95 % to 2.65 % during 3 months storage time at room temperature. Other stopper mixtures show an increase up to 1.7 %. Pikal and Shah [1.87] demonstrated, that the desorption of water from the stopper and the absorption of water by the product depends, in the equilibrium state, on the mass and water content of the stopper and the water content and sorption behavior of the dry product. 

Figure 16.5. Supersaturation behavior, (a) Schematic plot of the Gibbs energy of a solid solute and solvent mixture at a fixed temperature. The true equilibrium compositions are given by points b and e, the limits of metastability by the inflection points c and d. For a salt-water system, point d virtually coincides with the 100% salt point e, with water contents of the order of 10-6 mol fraction with common salts, (b) Effects of supersaturation and temperature on the linear growth rate of sucrose crystals [data of Smythe (1967) analyzed by Ohara and Reid, 1973],...

Several models were proposed to show the effect of concentration of osmotic solution and temperature on the rate of water loss and gain of osmotic agent. Thus, a model developed [56] for the calculation of osmotic mass transport data for potato and water activity to equilibrium in sucrose solutions for the concentration range 10%-70% and solution/ solids range 1-10 showed that, at equilibrium, there was an equality of water activity and soluble solids concentration in the potato and in the osmosis solution. A linear relationship existed between normalized solids content (NSC) and log (1 - fl J and was given by... 

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