Why is it important to express the oils of a citrus peel over a drink?

Expressing the oils of a citrus peel over a drink is crucial because it significantly enhances the fragrance and flavor profile of the cocktail. The essential oils found in the outer skin of citrus fruits contain aromatic compounds that contribute to the overall sensory experience of the drink. When the oils are released, they provide a burst of citrus aroma that can elevate the taste, making the drink more vibrant and enjoyable. This aromatic quality complements the other ingredients in the cocktail and can greatly influence a drinker's perception of flavor.

The other options address aspects that are not the primary reasons for expressing citrus oils. For instance, adding color is not a significant impact of expressing oils; the goal is more about aroma and taste. Likewise, while citrus does add acidity, this effect is more related to the juice itself rather than the oils released from the peel. Additionally, texture isn't affected by the oils; the physical qualities of the drink are influenced by the components mixed within it, not just by the aromatic oils. Thus, enhancing the flavor and fragrance is the primary purpose of expressing citrus peel oils over a drink.