"Cold-brew" vs. Japanese Iced Coffee
“Cold-brew” vs. Japanese Iced Coffee
We love the science behind coffee, and we’re always looking to share the amazing story of this drink with our customers. Today, in honor of the first full week of summer, let’s talk iced coffee.
As we’ve said before, coffee is a rapidly changing industry. Just a few short years ago, if you entered a specialty coffee shop and asked for iced coffee you’d almost certainly get hot coffee straight from the airpot poured over ice. These days, iced coffee has become so popular that various methods have sprung up for serving this once obscure drink. You might be familiar with “cold-brew,” that dark, sweet liquid oft-served from a tap, but chances are you haven’t heard of the method we use at your favorite Queen City cafe: Japanese Iced Coffee.
There are some key differences between these two methods.
Cold-brew mixes cold water with ground coffee and brews all night long to create a concentrated, mellow drink. Japanese Iced Coffee, on the other hand, takes just a few minutes and has a brighter flavor you’d expect from a summer coffee drink. The Japanese Iced method is made with a Chemex (a form of pour-over), but instead of using just hot water poured over the grounds, half the water is already in the pot in the form of ice. The coffee gets the advantages that come with hot brewing, but is flash chilled as it drips onto the ice.
Bear with us for a second here, because we’re about to get a little technical. There are three components of iced coffee brewing that we’re going to examine: solubility, volatility, and oxidation.
Coffee is a solution. If you remember your high school chemistry, a solution is created when two or more substances are combined and the ability of solids to dissolve in water is called solubility. You may think of coffee as just water passed through grounds, but in actuality, it goes through some chemical changes during the brewing process. There are compounds in coffee that, when combined with water at just the right temperature, dissolve and become the solution that is the drink you love. The solubility of coffee decreases as the water temperature decreases, so when coffee is “cold-brewed,” the compounds that create coffee brewed with hot water remain in the grounds.
We brew our iced coffee hot, in order to grab onto those dissolvable compounds and create delicious coffee.
Volatility is the ability of substances to turn into gas, or vapor. Volatility also increases with temperature - which is why hot coffee smells so delicious. But whenever you smell coffee - those delightful aromatics are escaping into the air. The longer coffee sits around, the more those aromatic compounds are deadened. So we flash chill our iced coffee - sealing in those aromatics until the coffee is heated again. When would iced coffee be reheated? After you’ve taken a drink, of course! That’s why our iced coffee has such a delicious aftertaste, and why those aromatics creep back into your nostrils.
Finally, oxidation is a chemical change that happens to coffee oils (the source of the delicious flavors) when they are exposed to oxygen. Too much exposure to oxygen causes coffee to taste stale and/or sour. Oxidation occurs more quickly at higher temperatures - so flash chilling the Chemex decreases the opportunity for oxidation.
The beautiful, refreshing result
When we brew Japanese Iced Coffee what results is a delicious, refreshing alternative to hot coffee. This type of brewing is best experienced using bright and fruity coffees so expect to see us icing coffees originating in Ethiopia or Guatemala. The floral and fruity aromatics will still be present because our process allows for solubility, decreases oxidation and times volatility so that it happens on your tastebuds rather than before it even hits the cup. We hope you’ll stop in and try it soon.