Microfoam
Encyclopedia
Jargon
Jargon is terminology which is especially defined in relationship to a specific activity, profession, group, or event. The philosophe Condillac observed in 1782 that "Every science requires a special language because every science has its own ideas." As a rationalist member of the Enlightenment he...
, is a term used to describe an ideal standard for steamed milk, used for making espresso
Espresso
Espresso is a concentrated beverage brewed by forcing a small amount of nearly boiling water under pressure through finely ground coffee. Espresso is widely known throughout the world....
-based coffee
Coffee
Coffee is a brewed beverage with a dark,init brooo acidic flavor prepared from the roasted seeds of the coffee plant, colloquially called coffee beans. The beans are found in coffee cherries, which grow on trees cultivated in over 70 countries, primarily in equatorial Latin America, Southeast Asia,...
drinks, particularly those with latte art
Latte Art
Latte art is a method of preparing coffee created by pouring steamed milk into a shot of espresso and resulting in a pattern or design on the surface of the resulting latte. It can also be created or embellished by simply "drawing" in the top layer of foam...
. Although steamed milk can be made in a variety of ways, microfoam is by definition made using a steam wand on an espresso machine
Espresso machine
An espresso machine is used to produce the traditional Italian coffee beverage called espresso.-History:The first machine for making espresso was built and patented by Angelo Moriondo of Turin, Italy, who demonstrated a working example at the Turin General Exposition of 1884. He was granted patent no...
.
The qualitative opposite of microfoam is macrofoam (also called dry foam, in contrast to the wet foam of microfoam), which has visibly large bubbles, a style of milk commonly used for cappuccino
Cappuccino
A cappuccino is an Italian coffee drink prepared with espresso, hot milk, and steamed-milk foam. The name comes from the Capuchin friars, referring to the colour of their habits.- Definition :...
s.
Applications
The primary application of microfoam is in making latte art
Latte Art
Latte art is a method of preparing coffee created by pouring steamed milk into a shot of espresso and resulting in a pattern or design on the surface of the resulting latte. It can also be created or embellished by simply "drawing" in the top layer of foam...
– patterns in espresso-based drinks – and is essential for this. Latte art is traditionally associated with latte
Latte
A latte is a coffee drink made with espresso and steamed milk. Variants include replacing the coffee with another drink base such as masala chai, mate or matcha...
s (large drinks – 8–12 oz or more), as the name suggests, but can also be used in shorter drinks. If cappuccino
Cappuccino
A cappuccino is an Italian coffee drink prepared with espresso, hot milk, and steamed-milk foam. The name comes from the Capuchin friars, referring to the colour of their habits.- Definition :...
-sized (5–6 oz), this is sometimes known as a "wet" cappuccino, and latte art can also be made even in the small macchiato
Latte macchiato
Latte Macchiato is a coffee beverage, which literally means stained milk. This refers to the method of preparation, wherein the steamed "pure" white milk gets "stained" by the addition of espresso.- Related drinks :...
.
Microfoam may also be added to brewed coffee in a café au lait
Café au lait
Café au lait is a French coffee drink. The meaning of the term differs between Europe and the United States; in both cases it means some kind of coffee with hot milk added, in contrast to white coffee, which is coffee with room temperature milk or other whitener added.- Europe :In Europe, "café au...
, and faint latte art can be produced. Microfoam may also be used in a steamer, though this can instead be made with dry foam.
By contrast, microfoam is not necessary for traditional "dry" cappuccinos, which instead have a layer of dry foam floating on top, nor is it necessary or generally used in latte macchiato
Latte macchiato
Latte Macchiato is a coffee beverage, which literally means stained milk. This refers to the method of preparation, wherein the steamed "pure" white milk gets "stained" by the addition of espresso.- Related drinks :...
s, which also typically have separate layers of dry foam and liquid milk.
As producing microfoam, and a fortiori latte art, requires a skilled barista, it is a sign of attention to quality, and a defining characteristic of Third Wave Coffee
Third Wave Coffee
The Third Wave of Coffee refers to a current movement to produce high-quality coffee, and consider coffee as an artisanal foodstuff, like wine, rather than a commodity, like wheat...
.
Procedure
Foam
-Definition:A foam is a substance that is formed by trapping gas in a liquid or solid in a divided form, i.e. by forming gas regions inside liquid regions, leading to different kinds of dispersed media...
(also called "froth") is created.
The foam content is controlled by the barista during the steaming process, and involves two phases: first, introducing air ("frothing") by having the steam tip near the top of the milk, and second, mixing the incorporated air throughout the milk ("mixing, texturing"), which is achieved by having the steam tip immersed more deeply, creating flow or a "whirlpool" in the milk. During the steaming process, the foam phase is both primarily created at the top, and naturally separates from the liquid phase, and rises to the surface. As a result, after the steaming ends, the mixing often continues by swirling the pitcher in a smooth, circular motion until the mixture of foam and warmed milk becomes homogenous, before being added to a drink.
Too much foam, or foam that is not sufficiently mixed with the milk, creates "dry" foam and a totally white surface on a drink (see cappuccino
Cappuccino
A cappuccino is an Italian coffee drink prepared with espresso, hot milk, and steamed-milk foam. The name comes from the Capuchin friars, referring to the colour of their habits.- Definition :...
), while not enough foam yields liquid, runny milk and creates a homogeneous, light-brown coffee drink, with no foam or patterning, just like adding warm milk.
To pour latte art, the milk should be shiny, slightly thick, and should have very small, uniform bubbles. It is not particularly "foamy" – it is better described as "gooey" and closely resembles melted marshmallows. There have been a variety of names used for this ideal standard, such as "microfoam", "velvet milk", "microbubbles", and so forth.
The milk must not be overheated to the point that it is scalded
Scalded milk
Scalded milk is milk that has been heated to . At this temperature, bacteria and enzymes in the milk are destroyed. Since most milk sold today is pasteurized, which accomplishes both of these goals, milk is typically scalded simply to increase its temperature, or to change the consistency due to...
, as at this point the enzymes denature and the texture no longer works.
Physics
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
s such as casein
Casein
Casein is the name for a family of related phosphoprotein proteins . These proteins are commonly found in mammalian milk, making up 80% of the proteins in cow milk and between 60% and 65% of the proteins in human milk....
and whey
Whey
Whey or Milk Serum is the liquid remaining after milk has been curdled and strained. It is a by-product of the manufacture of cheese or casein and has several commercial uses. Sweet whey is manufactured during the making of rennet types of hard cheese like cheddar or Swiss cheese...
; the protein attracts and holds gas on its surfaces, creating microfoam. Strictly speaking, microfoam is actually a very fine foam
Foam
-Definition:A foam is a substance that is formed by trapping gas in a liquid or solid in a divided form, i.e. by forming gas regions inside liquid regions, leading to different kinds of dispersed media...
, a liquid-gas colloid
Colloid
A colloid is a substance microscopically dispersed evenly throughout another substance.A colloidal system consists of two separate phases: a dispersed phase and a continuous phase . A colloidal system may be solid, liquid, or gaseous.Many familiar substances are colloids, as shown in the chart below...
of milk and air, which has few or no visible bubbles, and is stabilized by the denatured milk protein.