It is typical for espresso shots served in Mediterranean regions to be topped with a browned layer of foam known as crema, which is especially indicative of authentic Italian espresso. It imparts an aromatic quality to the flavor and a tactile, mouth-feeling quality to the food.
The crema on a latte and the crema on a cappuccino made with steamed milk look quite similar, but the former thins out as it cools, while the latter thickens and turns marbled as it chills. You can watch this happen as the milk is heated, as the air bubbles rise to the top of the steamed milk, and then compact together as the milk cools, creating a crema with a deeper texture.
The following are some of the reasons why latte makes a great “crema” (brown emphasis):
When milk is heated, a process called the Maillard reaction causes the surface layer to cook and turn a dark caramel color. This is an extremely prized component since it greatly enhances the concentration of flavor.
At 230 degrees, the raw fat droplets in the heated milk boil.
When espresso is poured into milk that has been heated to a boil, a foam called a latte crema forms. The emulsion pulls together fat molecules and distributes them throughout the mixture, creating a natural microfoam that masks the true nature of the liquid.
Raw milk, which is typically used to make lattes, is typically much thinner in texture than the conventional milk used in the United States, giving the beverage a bright white hue. The chemical processing and reduced exposure to light (refrigerator or sunlight) give crema its distinctive nutty flavor.
When translated literally from its Italian origin, crema means “the cream.”
When the espresso heats the milk, it rises to the foam on top and penetrates it, creating a latte’s signature crema. Crema is the dense foam that sits atop a classic espresso shot and is typically about a quarter of an inch in height. Crema contributes to the flavor, texture, and thermal retention of espresso, making it a must-have ingredient.