Final answer:
Sugar stabilizes the foam structure in meringue and whipped cream by dissolving and interacting with proteins, helping the foam to hold its shape and making it suitable for use in desserts.
Step-by-step explanation:
Aside from adding sweetness, sugar plays a crucial role in the creation of meringue and whipped cream by helping to stabilize the foam structure. When sugar is beaten together with egg whites, it dissolves and interacts with the proteins, which helps to form a stable, glossy, and strong foam that is capable of holding its shape. This stabilization is essential for desserts that rely on maintaining their form, like meringue toppings for pies and delicate whipped cream decorations on cakes. Without the addition of sugar, the foam would be less stable and could collapse or weep, which would not be suitable for desserts.