TSG Tip: Cold Brew 101

Iced coffee is the caffeinated beverage of choice for many during the summer months. But preparing a good cup takes a little more effort than pouring your leftover morning brew over ice. As many coffee connoisseurs know, the method that produces the best flavor and perfect balance of caffeine is cold brewing. We caught up with Jonathan Adams, co-founder of Philadelphia’s cult-favorite Rival Brothers Coffee Roasters, for the lowdown on perfecting your cold-brewed cup at home.

Consider the science behind cold-brewed coffee. In traditional hot coffee, hot water is introduced briefly to coffee grounds. This process is perfect for a hot cup, but not ideal for iced coffee. In order to extract the optimum amount of flavor, the water and grounds need to commingle a while—something you would never do with hot water, because the coffee would end up terribly bitter. “The result is a smoother, rounder coffee with less tannins and a lower pH,” Adams says.

Know that cold brew is high octane. Heat kills caffeine, Adams explains, so the resulting cold brew has a higher level of caffeine, which is why some choose to dilute it with water or milk. Also of note, the lower pH in cold brew makes it less acidic and easier to digest, so those who suffer from digestive issues may choose to add hot water to a cold-brew concentrate for a more traditional cup of coffee.

Remember that the beans matter. “At Rival Bros., we use a proprietary, espresso blend that tends to be a little bolder and darker and has a nutty, chocolate flavor,” Adams shares. When sourcing coffee, look for a medium plus espresso blend made from beans that have a matte finish with a little bit of sheen on them. Adams advises that you keep two things in mind when shopping: first, oily beans are the result of a dark roast, and these tend to lose their sweetness—which is not optimal in a cold brew; second, lighter roasted beans will result in a brew that is sour and opaque and not at all desirable.

Go for a coarse grind. Because the grounds and coffee are going to mingle for a spell, it’s best to opt for a coarse grind, which will minimize the likelihood that you’ll end up with tiny particles floating around in your glass. “Cold-brew coffee is made by a process called immersion brewing, like in a French Press preparation,” Adams explains. “In order to easily extract the grounds, they can’t be too fine.”

Follow a set of guidelines for your perfect cup.  “I don’t recommend a specific recipe, but brewing parameters,” Adams notes. “Personal taste varies, so it’s really best to observe a rule of thumb and tweak to what you prefer.” He also says that you don’t need a fancy vessel; a large Mason jar works perfectly. Here is Adams’s cold-brew framework:

  • Brew ½ pound of coarsely ground coffee to ½ gallon of filtered water.
  • Add coarse grounds to your container and fill with water.
  • When you first add water, the grounds will release carbon dioxide and puff up. Counteract this process by punching grounds down with a spoon and then stir.
  • Allow jar to sit at room temperature for 18 to 24 hours. (Placing in the refrigerator slows down the brewing process.) Note: Brewing time depends upon the roast of the bean. The time recommended above is for a medium plus espresso blend. If you have a dark roast, you won’t want to brew longer than 12 hours or the resulting coffee will be bitter. For a lighter roast, you’ll want to brew for longer, but never more than 24 hours.
  • After your brewing time is up, pour the coffee first through a sieve or fine colander to capture the largest grounds and then strain through two layers of cheesecloth.
  • Store in the refrigerator for up to a week.

Give drinking it black a shot. Whether you choose to cut your cold brew with water is up to you. “In our stores, we just fill a cup with ice and pour coffee over it. As the ice melts, it tends to dilute it a bit,” Adams says. He also recommends that you try cold-brewed coffee without sweetener or milk. Because of the brewing process, you may find that this preparation lacks the bitterness you’ve come to associate with coffee, and that is has an added natural sweetness. However, you can certainly add milk or an alternative. For sweeteners, he says it’s best to opt for simple syrup, brown sugar, or maple syrup, as these will dissolve better in cold coffee. “But we don’t ever judge,” Adams notes. “Add sweetened condensed milk a la Vietnamese coffee, or try oat milk and a simple syrup with lemon and rosemary. Experiment with different flavors to find your perfect cup.”

TSG Tip 272 from Jonathan Adams of Philadelphia’s Rival Brothers Coffee Roasters. Rival Brothers Coffee Roasters is featured in the The Scout Guide Philadelphia.