The collapse mechanism of meringue was studied to elucidate the effect of sucrose on the structural stability. Meringues with different sucrose concentrations were prepared and observed both in horizontal and vertical directions. In the sucrose-free system, bubbles gradually collapse without abrupt structural change. With the addition of sucrose, the meringues showed discontinuous collapse characterized by abrupt structural changes. This behavior was attributed to the interplay between plateau border thickness, viscous stress of the egg white solution, and mechanical balance of tensions acting on the plateau borders. Addition of sucrose increased the solution viscosity, which reduced the mobility of plateau borders. Reduced mobility reduces their ability to resolve local imbalance of tension. This prevented immediate rearrangement of bubbles, which enhances the mechanical instability of meringues resulting in eventual abrupt collapse. At higher sucrose concentrations, a further increase in the solution viscosity provided more resistance to the imbalance of tension, which suppresses the abrupt collapse and increases the stability of meringues.
Soutome et al. (Wed,) studied this question.