By Hannah M. Hartge, Eckhard Flöter and Thomas A. Vilgis
The aim of this study was to better understand the (non-equilibrium) physics of fondants (Hartel & Nowakowski, 2017) at the microscopic level in order to be able to control processes more precisely. For this purpose, simple model systems consisting of water and sucrose were investigated.
Fondants, special sugar glazes or pastes, have a silky mouthfeel that is created by tiny crystals dispersed in a saturated syrup (Lees, 1965, Porter & Hartel, 2013). The relation between the high viscosity and small crystal size is the decisive physical parameter. This exceptional state can only be achieved with supersaturated sugar solutions, coupled with a complex kneading process and temperature control. This results in a metastable state that balances the syrup concentration and crystal size distribution.
In practice, a fondant is produced by reducing a hot sugar syrup to high concentrations of 80 – 92% sucrose by weight, cooling it, and stirring or kneading the supersaturated system. Stirring causes rapid nucleation and crystal growth, while at the same time – under the right conditions – limiting the size of the resulting crystals to between 1 and 20 µm in diameter, so that they are not perceived as disturbing during oral processing.
