Cold brew coffee: Good things come to those who wait

The Yomiuri Shimbun
Barista Tomoyuki Takai adjusts the flow of water on a dripper at Kurumed Coffee in Kokubunji, Tokyo.

Cold brew, a type of coffee made by steeping ground coffee beans in room-temperature water, has been garnering a loyal following for its mellow flavor profile and smooth aftertaste. Although time-intensive to make, the opportunity to slow down and savor the process may be part of its appeal. As the temperatures climb, cold brew is poised to be the drink of the summer, whether enjoyed at a coffee shop, or imbibed by the potful at home.

Upon entering Kurumed Coffee, the first thing that catches the eye will be the six towering drippers for cold brew coffee, arrayed in a tidy row along a wall of this coffee shop in Kokubunji, Tokyo. Each of the contraptions measures nearly a meter tall and contains a distinct roast, reflecting the array of offerings on tap on the day’s menu.

As water drips from the tank atop the tower, it passes through a chamber containing coffee grounds, slowly extracting the essence locked within the beans, drop by patient drop. Optimal water flow depends on the roast and the fastidious baristas at Kurumed Coffee go so far as to calibrate the drip speed of each tower with a metronome. All told, it takes about six hours to brew a pot of coffee using this method.

Having sampled some of their cold brew, I can confirm it is well worth the effort. The coffee’s slight acidity balances out its bitter notes, with a delectably rich aroma.

“Cold brew coffee is uniquely refreshing. I want customers to be able to experience the full breadth of flavors that arise when you really give them time to develop,” said barista Tomoyuki Takai.

Known as “mizu-dashi” in Japan, cold brew is, as the name suggests, made with cold or room-temperature water. The technique is different from iced coffee, which is first brewed with scalding water, before being cooled and served over ice.

The Yomiuri Shimbun
A clean, refreshing glass of cold brew coffee served at Kurumed Coffee

Yukio Hirose, chairman of the Japan Coffee Society and a professor emeritus at Kanazawa University, explained: “[Using cold water] instead of hot water helps to slow oxidation, meaning it can still be enjoyed long after extraction. A clean finish and mild acidity are other defining characteristics.”

Hirose says that there are many different theories about the origin of cold brew coffee. Centuries ago, Indonesians are thought to have begun soaking their grinds in cold water to remove bitterness. As Indonesia was formerly a colony of the Netherlands, cold-water extraction has also been called “Dutch coffee.” But in recent years, the term “cold brew” has quickly become a familiar fixture on menu boards across Europe and the United States.

Thanks to a wide variety of commercially available products, cold brew enthusiasts can now get their daily fix in the comfort of their own homes.

Mari Tsujimoto, an employee of the heat-resistant glass manufacturer Hario, says that there are two broad categories of product for the home consumer. One is a “dripper,” which percolates the coffee drop by drop. The other is a “soaker,” which steeps the grounds to create a concentrated elixir.

Although Tsujimoto recommends using deep-roasted coffee beans for the best results, she says that no special technique is necessary. “You can even experiment with adding a sweet bouquet by soaking orange slices or other fruit along with the coffee, simply pop in your favorite flavor,” she said.

Milk brew, too

Coffee can also be brewed with milk instead of water to particularly luxurious results.

“Milk brew coffee better enhances the aroma of coffee than cafe au lait,” said Nobutaka Kato of Base Coffee, a roastery in Ichinomiya, Aichi Prefecture.

The process is simple. Place coffee grounds in a porous pouch, such as a tea bag or cheesecloth, drop it in a jug of milk, and let cool in the fridge. Aim for a coffee-milk ratio of 1 to 10. For example, 30 grams of coffee beans for 300 milliliters of milk.

To let the coffee sing, a light roast is recommended. The richness of milk, with its high fat content, makes milk brew a match made in heaven. Six hours is a standard extraction time, Kato says, so plan ahead and resist the temptation to sneak a sip.