What role does the frothed milk play in a cappuccino?

Frothed milk plays a significant role in a cappuccino primarily by acting as an insulator. When frothed milk is added to espresso, it creates a barrier that helps retain heat, keeping the beverage warm for a longer period. The velvety texture of the frothed milk not only contributes to the overall mouthfeel of the drink but also moderates the intensity of the coffee flavors, creating a balanced experience that is both creamy and rich.

In addition, the incorporation of froth adds a layer of air into the milk, which transforms its texture and enhances the drink's aesthetic appeal. This helps to create the characteristic foam top of a cappuccino, which can also affect the taste perception, making it smoother and less harsh than espresso alone. The approach of using frothed milk in this way is fundamental to achieving that classic cappuccino experience.

Considering the options, the other roles attributed to the frothed milk do not align with its primary function in a cappuccino. Enhancing sweetness, increasing bitterness, or adding acidity are not typical characteristics influenced directly by the frothed milk; instead, these aspects may derive more from the coffee itself or other ingredients used in different contexts.