Japanese iced coffee, also known as flash-brew coffee, is a distinctive way of brewing iced coffee that involves brewing a hot coffee concentrate directly over ice. Even though Japanese iced coffee may visually look the same as regular iced coffee or cold brew coffee, this specialty type of iced coffee uses a flash chill process designed to preserve nuanced flavors for a balanced, finished cup.
So, what exactly is Japanese iced coffee, how is it brewed, and what makes the process different? Let’s examine this iced coffee brewing method’s origins and learn how to try it at home.
What is Japanese iced coffee?
Japanese iced coffee is a hot coffee concentrate brewed directly over ice, using a flash chill process. “Iced coffees, cold brews, iced Americanos, and Japanese iced coffee are four distinct brewing processes that create different cold coffee experiences,” says Callie Petrocine, Barista Market Developer Lead at Oatly North America. Petrocine leads Oatly’s North American Food and Drinks Experience (FADE) Department.
When asked about Japanese iced coffee, she explains that the key difference (when compared to other cold coffees) is in the brewing method. “Unlike iced coffee, the flash chill process preserves more of the nuanced flavors, and it can be enjoyed immediately. The hot coffee is brewed at a higher concentration to account for the added ice, creating a balanced finished cup,” she shares. In comparison, traditional iced coffee is usually made by brewing hot coffee, pouring it over ice, or putting it into the fridge to get cold. This results in a different flavor with more acidity and brighter flavor compounds, as the coffee was brewed hot originally.
Origins of Japanese iced coffee
“As the name ‘Japanese iced coffee’ suggests, this method originated in Japan in the 1920s, where it was traditionally served with milk, says Petrocine. There has been a global resurgence of this brewing style due to the speed and ease of making a delicious, cold coffee. We’re seeing slight variations pop up all over the world under different names like “flash brew” and “chillter” (a portmanteau of chilled and filter), for instance.
The core technique used to make Japanese iced coffee is a pourover method, which uses hot water and ice to brew a cup of cold coffee. “The total liquid volume you will use for your recipe will be split between the hot water used to brew the coffee concentrate and the ice in the bottom of your brewing vessel, which will flash chill and dilute the hot brewed coffee. You will need a V60 or Chemex brewer, hot water kettle, food scale, coffee, burr grinder, filtered water, paper filter, and ice.
How to make Japanese iced coffee
The world of cold coffee today offers many options, from nitro cold brew to iced flat whites. So, what makes Japanese iced coffee a great choice? For Petrocine, this brewing method creates the best extraction for light to medium roast coffee and offers a quick way to have a cold coffee on a hot day. She loves that this method is easy to replicate at home using a Chemex brewer.
Selecting coffee beans
Every coffee lover knows the importance of selecting the proper roast of coffee beans for their brewing method. Choosing the right beans goes a long way to ensuring the best possible flavor for your cup of coffee. In the case of Japanese iced coffee, Petrocine recommends using light or medium roast coffee beans, as this brewing method excels at preserving the inherent acidity and delicate flavors of these coffee roasts. She also recommends Puerto Rican coffees, due to their unique flavor profiles and recent rise in popularity. “If you can’t source them, opt for any high-quality, in-season coffee with flavor notes that you enjoy. Ultimately, the best choice is what sounds most delicious to you,” she notes.
Steps to make Japanese iced coffee
To make Japanese iced coffee, “I typically use a 1:16 coffee to water ratio. If you would normally make a 12oz pour over using 25g of coffee and 400g of water, you will split your 400g of water between the hot water to brew the coffee and ice to chill it. A nice split is 150g of ice in the bottom of your brewing vessel and 250g of hot water to brew your coffee concentrate. If your ice cubes are a bit larger, try to get as close to the split as possible and adjust your hot water accordingly to ensure that the final recipe has 400g total of ice and water. Use your scale to ensure accuracy. Once you’ve brewed your coffee concentrate into your vessel of ice, swirl to combine until the ice has fully dissolved,” she shares.
The total brew time should be about 3 minutes (including a 30-second bloom) and 1-2 minutes longer if you double the recipe. If it’s taking too long to brew, coarsen your grind size to avoid bitterness (over-extraction). If it’s brewing too quickly, make your grind size finer to avoid sourness (under-extraction).
