What is cold brew coffee (and how is it different from iced coffee)?
Cold brew uses room-temperature or cold water (the latter will take longer) throughout the entire process, and extracts the coffee much more slowly, sometimes up to two days. The result is a richer, smoother, and less-diluted coffee concentrate that can be watered down or mixed with milk, while preserving the flavor of that coffee you paid good money for. “Iced coffee, on the other hand, is brewed hot and then cooled, or brewed directly over ice,” Megan Biolsi, Manager of Coffee Education and Training at Sightglass Coffee, told me. “Because it uses hot water, it retains more brightness and acidity, resulting in a more vibrant and aromatic cup that is closer in profile to hot coffee.”
Why does cold brew take so long to make?
“Cold brew is essentially a long, gentle immersion brew,” Biolsi explained. “Similar to a French press, the coffee grounds remain in contact with water throughout the entire process. Because of the lower extraction energy from colder temperatures, the contact time is extended to achieve proper extraction.”
Brewing coffee low and slow isn’t pointless, in fact it’s the whole point. “At these lower temperatures, the extraction of flavor, caffeine, and oils happens more slowly,” Biolsi said. “However, this extended steep time results in a smoother, sweeter, and lower acidity coffee, since many of the more acidic compounds are less soluble in cold water and remain behind.”
That’s why we balk a bit at the machines that promises rapid, quick, or instant cold brew. As Major Cohen, an author and coffee educator at Cumulus Coffee, explained when I asked him to outline the difference he sees comparing the Cumulus process to some of the vacuum cold brew contraptions I’ll mention below, “Most of these countertop machines are not creating cold brew. Rather they are brewing traditionally and then chilling the result, which is a different product flavor-wise.”
“The faster brew time allows more acidic compounds to be extracted compared to true cold brew, so the result won’t have the same smooth, sweet, and balanced profile,” Biolsi “However, it may still be more full bodied than standard iced coffee.” Hence, we’ve included some of these quick cold brew machines in our reviews below.
How to make cold brew
A simple immersion brewing method is similar to making iced tea: Coarse coffee grounds sit in cold water for a long period of time—you could even just do this in a French press if you wanted. But a few brewers, including our winner, use gravity to gradually expose the water to the coffee grounds before filtering. We tend to prefer this style of cold brewer because most of the “steeping” methods rely on mesh or perforated metal filters that leave some unpleasant silt in your cup at best and, at worst, produce weak or bitter coffee.
Frequently the directions that come with these cold brew makers produce cold brew concentrate (like for our winning Oxo pick), which can be watered down or mixed with milk to your preferred strength and liking. You’ll want to experiment with your own ratios, but for concentrate, a coffee-to-water ratio of around 1:4 is a good place to start.
“Using consistent brew ratios, fresh coffee, and controlled extraction times will yield the best results,” Biolsi stressed, noting that precision is the name of the game. “Measure your coffee and grind it right before brewing whenever possible. Pre-ground coffee oxidizes more quickly due to increased surface area exposure. For grind size, use a coarse grind (similar to sea salt) to limit over extraction. If your brew tastes bitter (a dry sensation on the palate), adjust to a slightly coarser grind. If it tastes sour (a puckering or tingling sensation), adjust to a slightly finer grind.”
How we tested cold brew coffee makers
Using the same whole beans and filtered water, I followed the brewing instructions, grind recommendation, and measurements for each individual coffee maker. Unless otherwise noted in the instructions, I brewed each system in the refrigerator for a full 24 hours. For a second round of testing, we brewed every system on the countertop at room temp for 18 hours. For “rapid” cold brew makers that utilize battery-powered vacuum pumps, we brewed at any and all available extraction time settings. Testers tasted all of the resulting cold brew black and diluted with milk.
What we looked for in cold brew coffee makers
This refers to multiple factors, like setup, brewing instructions, cleaning, and how generally fiddly all the pieces are to put together and take apart. We also noted whether the recommended ratios and measurements produced good coffee, or whether we had to tinker with the formula, something we didn’t think beginners should have to worry about.
The point of cold brew is to achieve a rich, smooth coffee. We noted anything bitter or otherwise unpleasant.
Not only should the cold brew system feel sturdy, it should also stand up to repeat washings and, ideally, avoid small, easily breakable components.
Does the pitcher or system look attractive, or is it more utilitarian? How much counter or cabinet space does it take up?
Other cold brew coffee makers we tested and liked
Oxo Brew Cold Brew Coffee Maker
OXO Good Grips 32 Ounce Cold Brew Coffee Maker
This cold brew system is the larger cousin to our top pick, and its sheer size is its only real drawback. In addition to its footprint, it’s not the most attractive thing to keep around on your counter, looking more like a classroom science experiment than cool tech. We also wish the “Rainmaker” reservoir had a top on it to keep stuff out of the water. But it makes good coffee. If you’re consistently making cold brew for a bunch of people (or you need a bunch of cold brew to get through your day—we’re not judging), this larger capacity, 32-oz. coffee maker will fit the bill.
