Barista Techniques: How to Perfectly Froth Milk and Essential Tips to Consider

Frothing Milk: The Art and Science Behind Perfect Microfoam

Frothing milk is a crucial step in making a good latte. Novice baristas often accidentally make the foam too thick. So how exactly can you create a pitcher of perfect milk foam? The stability of milk foam is affected by casein micelles and whey protein in milk proteins. The presence of casein micelles creates tension on the milk's surface. When steam hits the milk surface, numerous bubbles of various sizes form. Then, adjusting the position of the steam wand creates a vortex in the milk that "chops up" larger bubbles, resulting in fine foam with a smooth texture. Normally, whey protein has a hydrophilic exterior, which gradually "unfolds" through stirring or heating, exposing its hydrophobic parts. These parts adhere to the created bubbles, reducing surface tension and slowing down the bursting speed, making the foam more stable.

Common Issues in Milk Frothing

Below are some common problems that can occur during milk frothing:

Issue 1: Milk Splashing During Frothing

This is a very dangerous situation. When learning to froth milk, beginners don't have stable control over the angle of the steam wand and the depth of the steam tip (hereafter referred to as the steam tip) in the milk. This can lead to splattering when steam is first turned on or when hands become unsteady later in the process, causing excessive movement of the milk pitcher and allowing the steam holes to contact the milk surface, which makes the milk splash out.

Solution: Always keep the milk pitcher in contact with the steam wand.

When beginners cannot stably control the movement of the milk pitcher, FrontStreet Coffee suggests using the pitcher's spout as a pivot point, allowing the edge of the pitcher to remain in contact with the steam wand. Whether you need to adjust the angle of the pitcher or move it up and down later, always maintain contact between the two to avoid suddenly having them "separated," which would cause steam to escape from the milk.

Issue 2: Foam is Not Fine Enough

What frustrates beginners isn't unsuccessful latte art, but rather foam that never becomes fine enough, with many large bubbles. When mixed with coffee, this creates an unpleasant drinking experience.

Solution: Turn on the steam briefly before frothing the milk.

When steam in the steam wand of a semi-automatic coffee machine cools down, it becomes water that remains in the wand. Therefore, before each milk frothing session, please purge the steam first until no water sprays out from the wand. Milk frothed with steam containing water will produce large bubbles.

Position the steam wand in the pitcher at a 45-degree angle.

A 45-degree angle means positioning the steam wand toward the 2-3 o'clock or 9-10 o'clock direction of the pitcher. Using this angle to froth milk helps create a small vortex quickly, and the appearance of this vortex can "pull in" coarser foam to the surface.

Place the steam tip 0.8cm-1cm deep into the milk surface.

The steam tip shouldn't be placed too deep, as milk frothing is primarily about incorporating air into the milk. If it's too deep, the steam holes cannot contact air to create a vortex. If it's too shallow, steam will impact the surface, creating rough bubbles and causing milk to splash.

Issue 3: Milk Foam is Too Thick

The thickness of milk foam depends on the foam created when steam properly contacts the milk surface, a process we call aeration. The longer the aeration process, the more foam is produced, and the thicker the milk foam becomes.

The aeration process only needs 4-5 "hissing" sounds.

Adjust the steam tip depth to 0.3cm and turn on the steam switch. You will hear a "hissing" sound. This is the aeration stage. For latte art, the ideal foam thickness is 1cm, so we don't need excessive aeration. After hearing 4-5 hissing sounds, adjust the steam wand depth back to 0.8-1cm, maintain the 45-degree angle to create a vortex that eliminates coarse bubbles while heating to the appropriate temperature.

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473