Final answer:
It is true that a properly baked hard meringue may color slightly on the edges due to the Maillard reaction. Vanilla extract does not cause this coloring, and while humidity affects the baking process, it does not directly result in edge coloring.
Step-by-step explanation:
The question is related to the characteristics of a properly baked hard meringue. When making a meringue, the goal is to achieve a crisp exterior and a light texture. It is true that a properly baked hard meringue will still color slightly on the edges. This slight coloring is an indication that the meringue has been baked enough to develop a little bit of color while remaining dry and crisp on the inside. This color change is the result of the Maillard reaction, a chemical reaction that occurs between amino acids and reducing sugars that gives browned foods their desired flavor. It is worth noting that vanilla extract, if used, does not typically cause the edges of a hard meringue to color. Also, while the humidity can affect the baking process by introducing more moisture into the environment, it would not directly cause the edges of the meringue to color.