What Are the Differences Between Latte, Cappuccino, and Flat White Milk Foam? Important Details for Frothing Milk and Creating Latte Art

When making hot milk coffee, frothing milk is an essential process. There are various types of milk coffee, with common ones including latte, cappuccino, and flat white. Obviously, knowing only one method of frothing milk is not sufficient.

What Are the Differences in Milk Foam Among Common Milk Coffees?

Besides having clear distinctions in cup sizes, milk foam thickness is also an important characteristic that distinguishes latte, cappuccino, and flat white coffees.

Among these three, cappuccino has the thickest foam, generally about 1-2cm thick. Its most distinctive feature is being "11 parts full," meaning the cappuccino's foam rises above the cup rim, creating a prominent hamburger-like shape. The thinnest foam is found in flat white coffee, approximately 0.3cm thick. Precisely because flat white coffee has very little foam with low tension, even when filled to capacity, it only reaches level with the cup rim, hence earning the name "Flat White" (Flat means "level" or "even").

Latte's foam thickness falls between these two, approximately 0.5-0.7cm thick. The foam thickness of latte coffee is very suitable for latte art. One of the reasons FrontStreet Coffee chooses wide-mouth cups when serving latte coffee is to better create latte art patterns.

How to Froth Milk to Different Thicknesses?

Now that we understand the different foam thicknesses required for various styles of milk coffee, let's understand the principle behind frothing milk with the steam wand we typically use.

The high-temperature steam ejected from the steam wand, if entirely injected directly into milk, will rapidly heat the milk. If part of the steam wand's outlet holes are submerged in milk while another part is exposed to air, the high-temperature steam will inject air into the milk. The proteins in the milk then encapsulate this air, forming milk foam.

During daily milk frothing, the steam wand is positioned at one side of the milk pitcher, forming an angle. When the steam is activated, the bursting steam creates a directional vortex within the pitcher, effectively controlling the frothing rhythm. Without forming a rotating vortex, it becomes difficult to control both the amount of foam and its fineness.

The thickness of the milk foam is determined by how much air is introduced. The more air introduced, the thicker the foam; the less air introduced, the thinner the foam. If all steam holes are submerged in milk throughout the entire process, then the whole process is merely heating the milk without producing any foam.

How to Judge the Thickness of Milk Foam?

1. Judging by the "Hissing" Sound

During the milk frothing process, we hear a "hissing" sound. These sounds are precisely the noise made by air being injected into the milk. Therefore, we can sometimes determine the foam thickness by listening to the sharpness and duration of this sound.

For example, when frothing milk for flat white coffee, the "hissing" sound typically lasts less than 2 seconds. For latte coffee foam, the "hissing" lasts about 3 seconds. For cappuccino coffee, the "hissing" lasts 5-7 seconds.

2. Judging by Volume

FrontStreet Coffee believes that judging by volume is a relatively accurate and easily recognizable method. Milk increases in volume after frothing, which includes the milk itself, steam injected by the steam wand, and the resulting foam. Basically, the steam ejected from the steam wand can be ignored, so the increased volume is actually the frothed foam.

FrontStreet Coffee calculates milk volume based on filling the pitcher to 5/10 full (milk occupying 5-6/10 of the pitcher is a reasonable amount that's easy to froth). For flat white coffee, the foam only needs to be frothed to 5.5/10 full, with only a slight increase in visible volume after frothing.

Latte coffee foam needs to be frothed to 6/10 full. The foam thickness required for cappuccino coffee needs to be frothed to 8/10 full.

3. Judging by Fluidity

Fluidity is also an excellent method for judging foam thickness. Before frothing, you can shake the milk pitcher to feel the fluidity of the milk. Then proceed with frothing the milk. When frothed to the thickness needed for flat white coffee, its fluidity is almost indistinguishable from liquid milk, though you can see a thin layer of foam adhering to the pitcher wall.

Latte coffee foam thickness, when shaken, feels like light cream, still maintaining very good fluidity. Cappuccino coffee foam thickness, when shaken, resembles set yogurt - difficult to shake and with very poor fluidity.

Besides Thickness, What Else Should Be Noted When Frothing Milk Foam?

Regardless of foam thickness, all milk foams share a common characteristic: fineness. This brings us to the texturizing phase after frothing is complete. During texturizing, we need to submerge all steam holes in the foam layer, using the vortex created by the steam to break down large, coarse, easily-breakable bubbles into fine, stable small bubbles.

During the texturizing process, pay attention to the position of the steam holes - not too shallow and not too deep. Too shallow exposes them to air, continuing to incorporate more air. Too deep prevents the foam layer from becoming fine and smooth.

The optimal position is just enough to cover the steam holes without making any "hissing" sound. Only then can the ejected steam break down coarse bubbles within the foam layer, creating fine, smooth milk foam.

Finally, one last point: when finishing, first turn off the steam, wait for the vortex in the pitcher to disappear and calm down, then remove the steam wand. Otherwise, removing the wand while steam is still active will likely cause the foam to become coarse.

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473