Dirty coffee is made by extracting espresso over iced milk, creating a beautiful layered effect. Over time, the coffee liquid on top slowly encroaches on the pristine white milk, forming a lovely gradient inside the clear glass, as if the pure white milk has been dirtied.

Dirty coffee, in plain terms, is just a visually appealing iced latte with a special way of drinking it. However, its high aesthetic value has made it very popular. Some friends have followed tutorials to make Dirty coffee, but the result lacks the expected layering and instead mixes with the milk. What's going on here? Front Street has summarized a few common reasons.

- Choice of cup

The shape of the cup plays a significant role in forming the layers. Generally, a cup with a tall body and a small opening makes it easier to achieve the layered effect. If you choose a cup with a wide mouth and a shorter height, it will take longer for the coffee to spread across the entire surface, and there won't be enough distance for the coffee to "dirty" downward, making it less visually appealing.

It's best if the cup has been frozen beforehand, as this can both slow down the rate at which the coffee seeps downward and preserve the flavor and mouthfeel.

- Distance for receiving the coffee liquid

The most common issue is that the distance between the extraction handle and the cup is too long. During the espresso extraction, this causes the coffee to converge into a thin, elongated stream with greater impact force, piercing through the milk surface and making it difficult for the coffee to float on top and form layers. Therefore, to create a beautiful layering, you need to bring the cup close to the extraction handle; the closer to the liquid surface, the better the effect.

If machine limitations prevent you from directly receiving the extracted coffee, you can first pour the freshly extracted espresso into a small cup, then hold a small spoon just above the milk surface to create a buffer layer. Note that you must keep the concave side of the spoon facing up and slowly pour the coffee into the spoon; the coffee overflowing from the spoon will float on the milk surface.

- Insufficient coffee concentration

Many friends ask Front Street if a moka pot can achieve the same effect as an espresso machine. Unfortunately, the coffee brewed in a moka pot still has a significant gap in concentration compared to a coffee machine, let alone in terms of crema. Therefore, coffee brewed with a moka pot is not suitable as the coffee base for a Dirty.

It is generally believed that espresso with rich and fine crema produces a better layering effect in Dirty coffee, as the coffee liquid penetrates the milk more slowly, allowing ample time for photos.

- The milk is too thin

You can choose milk that is richer and has a stronger milky aroma. Milk that is too thin cannot support the coffee liquid, causing the two to blend together immediately upon contact, which not only looks murky visually but also lacks the rich mouthfeel you get in a café.

Based on Front Street's production experience, several common brands of milk on the market, such as Vitasoy, Wei Chuan, and Bright Fresh Pasture, are all good choices. Of course, if you have time, you can also make your own concentrated milk as a base, which is the often-seen ice brewed milk in cafés. Front Street has also detailed the production steps in a previous article. Concentrated milk made this wayDirtymore easily forms a stable layering, lasts longer when consumed, and has a unique salty cheese flavor.

Of course, some friends use a "ice brewed milk + fresh milk" method to create a milk with moderate concentration, which is also a good attempt.

The above content is compiled by CoffeeHunters, a coffee news website.