5.3: The water-sucrose system

Key features of the cytosol of cells are represented in the binary water-sucrose system. In practice, of course, cytosol compositions are much more complex. The equilibrium phase diagram for this system is shown below:

Due to kinetic factors, the equilibrium states shown in this phase diagram are rarely reached. Nucleation of sugar crystals is difficult, since the complexity of the sucrose molecule and the viscosity of the liquid make getting a critical mass of molecules with the right orientation uncommon. At high concentrations of sucrose the system becomes sufficiently viscous to be considered (at lower temperatures) as a glass.

The practical phase diagram is:

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