A Primer on Cold Brew Coffee and Where to Drink It Around Town
It's summer, or at least pretending to be summer, and thus the season for iced coffee. Almost every coffee shop will have a version: some clouded with dairy products and laden in sugar, invariably more expensive than a plain cup of joe, and slurped down far quicker. Leaving aside frozen concoctions and desserts disguised as drinks -- affogatos; Vietnamese coffee; Viennese coffee; and caramel-laced, whipped cream-based treats -- there are generally two ways in which iced coffee is prepared in specialty coffee shops: cold brew steeped for hours or hot brewed over ice (known as ice brew).
There is a significant difference between these methods, and they make for vast variation in the resulting aromatics, level of quinic acid, and, of course, taste. Many would-be coffee drinkers cite coffee's acidity as a stomach irritant and favor cold brew which lowers the pH level. For the few who are that sensitive, it's fortuitous, but is it really a primary selling point?
Hot coffee is indisputably acidic, and since the pH scale is logarithmic, the increase from a pH near 5.5 to 6.3 (see chart below) is significant. However, if coffee is considered especially acidic, then carbonated drinks, alcoholic drinks, juices, sports drinks, and many bottled waters, should be considered more so and avoided as avidly.
In the coffee world, and to some extent, the media, a debate has slowly brewed over which is the best method. For consumers, this mostly matters if you are brewing your own at home, but even if you don't, you may want to know which version you prefer for the next time you're looking for cold brew around town.
Comparing Brew Methods
Ice Brew (AKA: Japanese iced coffee, "flash brewed")
Hot-brewed coffee (not espresso) is rapidly cooled over ice and immediately drinkable because the ice is factored into the water-to-grind ratio. The operative word is "rapidly." The stuff you find in bodegas, street carts, and faux coffee joints, is not ice brew coffee; rather, it's hot-brewed coffee allowed to cool and oxidize, then served to customers in a cup of ice, still overpriced and underwhelming.
Those who champion ice brew coffee refer to the resulting style and complexity with wine-like terms such as aromatics, varietal character, and terroir. They claim that cold brew tends to be flat and loses nuance of flavor. Consequently, ice brew should ideally be drunk black, unadorned with milk or sugar.
Benefits: retains the character of the roasted beans; preparation time is not much longer than that for a pour over cup, and brew time is shorter by hours to days compared to cold-brewing; immediately drinkable without the need to dilute or adjust afterwards.
Cons: you still need sixth grade math knowledge on ratios. Since the ice will dilute the coffee, this must be factored into the ratio of water to grounds.
Proponents: Peter Guiliano (former director of coffee at Counter Culture), Sam Penix (Everyman Espresso), and Oliver Strand (New York Times).
Where to Taste: Hi-Collar, Everyman Espresso, and Gasoline Alley.