How to drink dirty latte when it is served hot

Hot Dirty is difficult but not impossible. The drink was built as a cold beverage: cold milk sits below hot espresso, and the density difference keeps the layers separate while the coffee slowly sinks. Heating the milk removes that contrast, so the two liquids blend quickly and the visual layering largely disappears.

Dirty comes from Katsuyuki Tanaka, who opened Bear Pond Espresso in Tokyo in 2009 and listed B.P Dirty at opening. He used a dark-roasted coffee pulled in a large dose and short time, watched through a bottomless portafilter, and stopped the shot as the stream turned pale. Tests with a chilled espresso and warmed milk reproduce part of the effect but not the full separation.

Since its creation, Dirty coffee has been served as a cold drink, using the density difference between cold milk and hot espresso to create a distinct layering of flavors. But many coffee enthusiasts have raised the question: can Dirty be made as a hot drink? This article starts with the hidden menu at Front Street Coffee, traces the origins and core production of Dirty, and takes an in-depth look at the feasibility of hot Dirty. Through testing, it uses a specially made ice ball to rapidly cool the espresso and heats the milk, attempting to replicate the layered effect and compare the flavor differences between the iced and hot versions. The article also discusses the limitations of hot Dirty in cafe service, answering for coffee lovers why hot Dirty is difficult to make a regular option.

Friends who know Front Street know that, in addition to the regular drinks listed on the blackboard, the shop also hides quite a few secret options, such as flat white, espresso, Dirty, and more. Guangzhou's weather fluctuates like an electrocardiogram, and an old customer at Front Street hesitated for quite a while before ordering, finally throwing out a soul-piercing question: "I don't want to drink it iced, but I specifically want Dirty. Why can't it be made hot?"

Dirty: I was born cold

Many people may think Dirty is an internet-famous drink that became popular around the "dirty culture" trend of 2018 and 2019, and therefore mistakenly assume it was a product of that period.

In fact, Dirty came from Mr. Katsuyuki Tanaka of Japan. In 2009, he opened the cafe "Bear Pond Espresso" in Kitashitazawa, Tokyo, and Dirty was already a signature product at opening, written on the menu as "B.P Dirty."

The key to this cup of Dirty is that Katsuyuki Tanaka used a rather unique espresso—"Angle Stain." He chose dark-roasted coffee beans and used a large dose and short extraction time to obtain an ultra-high-concentration, low-extraction espresso, and also deliberately used a bottomless portafilter, relying on visual observation of the extraction state (the color of the espresso changes from dark to light), removing the cup directly at the right moment. The uninterrupted stream of coffee then left tear-like marks on the wall of the cup, hence the name "Angle Stain."

Using this kind of espresso with iced milk to make Dirty not only makes the layering long-lasting and clear, but also lets you feel rich layers from bitter to sweet and from hot to cold on the palate. So Dirty has been made iced since the beginning of its invention, and precisely because of its drinking experience so different from other espresso drinks, it has transformed from an "internet-famous" drink into a perennial staple on cafe menus.

Is it feasible to make Dirty hot?

To figure out this question, you first need to understand the key to Dirty's layering: there is a density difference between cold milk and hot espresso, so the espresso sinks slowly and fusion is delayed. If you want to make Dirty hot, you need to heat the originally larger proportion of iced milk, while turning the espresso cold, swapping the temperatures of the two and maintaining the density difference, in order to achieve coffee-milk layering.

It sounds not difficult; heating milk only takes a moment, but making iced espresso is tricky. If you put the espresso directly into the refrigerator for rapid freezing and cooling, by the time it finishes cooling, the oils and a large amount of aromatic substances have long since dissipated; if you add ice cubes, it will dilute the coffee concentration, and the layering effect becomes impossible to discuss, turning Dirty into an ordinary latte.

So Front Street thought of the specially made ice balls that have often appeared in competitions in recent years. Ice balls that have undergone cooling treatment can rapidly cool the espresso and retain more flavor compounds. Without further delay, let's test it right away.

Prepare 150 ml milk; prepare to extract espresso; use a bottomless portafilter; two pre-chilled specially made ice balls; one 200 ml glass. (This test uses Warm Sun blend coffee beans, with extraction parameters of 19.8 g dose, 29 seconds extracting 38 g of coffee liquid.)

Step one: heat the milk to about 56°C (just slightly hot to the touch is fine)

Step two: pour the milk into the cup and prepare to receive the espresso

Step three: aim the ice ball at the bottomless portafilter and begin extracting the espresso.

Extraction complete, enjoy immediately!

Actual tasting: after the espresso rapidly cooled, the Yirgacheffe-like acidity in the Warm Sun blend became especially prominent. In the first sip, the milk flavor was almost imperceptible, and the layered mouthfeel of iced coffee and hot milk was distinct; by the second sip, the temperatures of the coffee and milk had become more uniform, and the bitterness of the espresso was rich; by the third sip, the entire cup of Dirty had become warm coffee-flavored milk.

Under the premise of also using Warm Sun blend coffee, the tasting performance of hot Dirty is slightly inferior to normal iced Dirty, and the production method is complicated and demanding (the specially made ice ball must be refrozen after one use). If you want to use hot Dirty to showcase the flavor of the beans, additional tuning and pairing are also needed, and when the output volume is small, it seems a bit more trouble than it is worth. This is why Dirty is always iced, and why no hot Dirty can be found for sale in cafe service.

- END - Front Street Coffee

No. 10 Bao'an Qian Street, Yandun Road, Dongshankou, Yuexiu District, Guangzhou, Guangdong Province

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