What Everyone Ought to Know About Iced Coffee & Cold Brew
Iced Coffee Vs. Cold Brew
In a Twitter-based tug-of-war, this year has witnessed a wave of kinetic conversation about coffee on ice — and all of this before summer hit. It’s a polarizing topic that has invaded social media and intrigued coffee lovers around the world.
Many are torn between methods, having known magical moments from both ice and cold brew, and we can’t help but agree. To navigate the discussion, we’ve explored the two main categories of iced coffee-making and asked what their loyal fans have to say in their defense. We won’t be lifting the arm of a single champion, but we’ll dance around the ring and let readers decide who deserves the belt.
Iced Coffee: Keep The Heat, Then Chill
Affectionately referred to as the "Japanese iced method", ice brew is an intuitive option with a twist. It recruits classic devices like the Chemex, V60, or AeroPress and rearranges the recipes by adding ice early. When fresh coffee — brewed hot — lands on the ice drop by drop, it’s cooled instantly. The immediate result is chilled coffee that’s abundantly aromatic, agreeably acidic, and ready to drink.
This method answers some longstanding concerns about coffee served cold:
Iced coffee requires a ton of grounds, right? Not this coffee. Unlike other methods, the goal here isn’t to produce a concentrate that has to be cut with milk or water. While we recommend moderate updosing, there’s no need to use an exorbitant amount of beans. Cold, ready-to-drink coffee is a cinch without huge adjustments to ordinary ratios.
How can this coffee be anything but diluted? Again, it helps to use a little more grounds than usual. And by introducing hot coffee to ice drop by drop, the coffee cools faster and doesn’t melt as much ice. Contrast this with pouring an entire cup of hot coffee over ice at once: the ice melts quickly, along with the dreams of the poor sap who’s staring at a watery brew.
What about all that bitter, flavorless iced coffee that restaurant chains serve? This is the result of a devastating chemical phenomenon called oxidation, which takes place when coffee sits for a long time. And it elevates this conversation to the high realm of science. Lab coats on.
Unlike humans, coffee in both its roasted bean and brewed form dislikes oxygen — in fact, they’re sort of enemies. As it turns out, oxygen is a rather oppressive element and terrorizes the naturally occurring oils in coffee, making them taste unpleasant. The longer coffee is allowed to interact with this gaseous menace, the nastier it will become. Incidentally, oxidation is accelerated at higher temperatures, such as those at which coffee is brewed.
" It’s essential, then, that iced coffee, when brewed hot, is cooled as quickly as possible. Brewing directly over ice achieves this wonderfully. "
But this chemistry lesson isn’t over just yet. In his endorsement of this brewing method, Peter Giuliano of Counter Culture Coffee the SCAA Symposium, offers a few more helpful terms. The concepts of solubility and volatility will prove useful in this conversation.
Solubility describes the ability of a substance to dissolve in a solvent — or, in the world of brewing, coffee’s ability to dissolve in water. The changes we see (clear water becoming dark) are related to solubility. As was also true of oxidation, solubility is ramped up at higher temperatures, which is what leads to the generally accepted notion that coffee should be brewed with water between 195 and 205 degrees Fahrenheit. To brew at temperatures below this range, as Giuliano argues, is to leave desirable solids undissolved. (But more on that later.)
Another concept, volatility, describes the ability of a substance to vaporize — or, in the world of brewing, coffee’s ability to go airborne. The changes we smell (strong aromas filling the air) are related to volatility. Volatility also increases at high temperatures (see the pattern here?), so by brewing with hot water and cooling quickly the aromatics of coffee can be released and recaptured.
For obvious reasons, ice brew has caught some serious attention in the industry. It’s simple, familiar, and supported by both taste and theory, which is always a satisfying combination. George Howell has described it as “the only way to do it” (Strand, June 2011) and Jason Dominy praises it for retaining the taste of regularly brewed coffee, only cold. Trying it for the first time, Giuliano remarked, “the aromatics that I was used to smelling in hot coffee, I could taste in iced coffee” (Giuliano, May 2012).
Iced Coffee Recipe
a la Prima
Convinced? The recipe below is one of our favorites, but there are also great guides available from Peter Giuliano, Terroir Coffee's George Howell, The New York Times' Oliver Strand, Batdorf & Bronson's Jason Dominy, and CoffeeGeek's Mark Prince.
You’ll need your favorite pour-over device with a filter; 60 grams of coffee, ground medium; 500 grams of hot water; 200 grams of ice; a pouring kettle; and a cup or carafe.
- Assemble pour-over apparatus as per usual.
- Rinse Filter.
- Add ice to receiving vessel. Large cubes are preferable to small chunks.
- Pour water, heated to 195-205°F, into coffee using pouring patterns and practices appropriate to filter cone type. (Bonus points for spelling your name.)
- Five hundred grams and 3:00-3:30 later, serve coffee in a glass of ice.
For more information about methods like this, refer to our Beginners Guide to Pour Over Coffee Brewing.
Cold Brew: Cool From The Start, Worth The Wait
Famed for dropping jaws and teasing appetites, this is the legendary method that boasts a brew time between 2 and 24 hours — and sometimes longer. It’s theatrical and nearly ostentatious, but deceptively simple, and can be enjoyed with or without fancy equipment. Coffee is extracted with cool water, introduced either by full, immediate immersion or a slow, steady drip. Should one survive the wait, they’ll enjoy a sweet, syrupy cup that sidesteps coffee’s normal acidity and goes down smooth.
Cold brew has its own posse of proponents, who love that it’s solved some of their dilemmas:
Coffee with cream is a classic, but something seems off when the "Japanese iced method" meets milk. What’s going on here? It’s a matter of personal preference, but whoever asks this question is on to something. Strand suggests that "cold brew complements the rich sweetness of dairy", while ice brew is just meant to be enjoyed au naturel (Strand, June 2012).
Offering ice brew by-the-cup asks a lot of an already-busy cafe, but customers love their coffee cold. Is there anything more efficient out there? Yes — and it doesn’t involve using the rancid leftovers from the last bulk batch. Cold brew only requires a little human involvement at the start and finish, and in between replaces the busy barista with the gentle prowess of time. Strategically scheduled brews can allow a cafe to supply a steady stream of chilled coffee without demanding the constant attention of its staff.
Does brewing with cold water line up with that earlier chemistry lesson? Positioning science over the senses is a dangerous move when it comes to coffee — tastebuds, not textbooks, should make these decisions — but it does help to let research inform the discussion. Lab coats again, please.
Defending cold brew, Lorenzo Perkins of Cuvee Coffee refers to an intriguing trend described in The Coffee Brewing Handbook by Ted Lingle: apparently the presence of generally unfavorable compounds (infamous for their long names) decreases at lower brewing temperatures. As Nick Cho (Wrecking Ball Coffee Roasters) points out, these results were seen at temperatures around 158°F, which isn’t exactly “cold”, but there seems to be a pattern here (Cho, May 2012). Perkins suggests that cold brew’s unique sweetness has something to do with the fact that nasty compounds shy away from cold water.
" Positioning science over the senses is a dangerous move when it comes to coffee — tastebuds, not textbooks, should make these decisions... "
As sweet as cold brew can be, coffee does have some positive compounds that are rather particular about being extracted only by hot water. Perkins’ quick fix: start hot, finish cold. His method splits the total water volume 80/20, reserving the smaller share for hot water and then continuing with cold brew as normal. By his estimation, this should extract all desirable solubles — those both deep and delicate — and minimize the presence of those less welcomed.
However, oxygen is impartial in its treatment of coffee and quickly trashes ice brews and cold brews alike. What, then, can be done about a method that requires several hours to sit and steep? Minimizing the coffee’s exposure to oxygen is a must, and can be achieved simply by using a container that holds only the desired volume of coffee and water and no more. For extra security the entire apparatus can be stored in an anaerobic environment. Dwelltime in Cambridge, Massachusetts is among the first to keep cold-brewed batches in a nitrogen-fed kegerator, a technique that Perkins also recommends.
But Dwelltime isn’t alone on the cold brew side — not even close. It’s gone from obscurity to all-star status in a few short years, and it’s still climbing the charts. Jay Caragay employs cold brew towers at his Baltimore cafe, Spro Coffee, and loves that his customers enjoy the visual excitement. (Uniquely, Caragay matches coffees to brew methods, so there is no monopoly of method at Spro.) Orange County’s Portola Coffee Lab also makes use of both ice and cold brew methods, but enjoys their Kyoto-style dripper for its distinct sweetness and the complexity that comes with constantly moving water.
Cold Brew Recipe
a la Prima
Care to give it a try? The recipe below is one of our favorites, but there are also great guides available from Cuvee Coffee’s Lorenzo Perkins, Barismo's Jaime van Schyndel, and Square Mile’s James Hoffmann.
You’ll need an AeroPress with 2 filters (at least one should be paper); 45 grams of coffee, ground medium-fine; 300 grams of water; 200 grams of ice; a water bottle (Dasani works well); a sewing needle, a sharp blade, and a mason jar.
- Empty water bottle and cut off bottom with sharp blade.
- Remove bottle’s cap and puncture with sewing needle, creating the smallest hole possible.
- Replace cap and test flow by filling with water and watching drip rate, aiming for about 40 drops per minute. Alter hole size as necessary.
- Rinse filter and assemble AeroPress, filling with coffee.
- Moisten grounds with warm water and mix gently, subtracting water used from total water volume.
- Level coffee bed with finger.
- Trim paper filter to fit inside of AeroPress tube and place atop coffee bed, pressing softly to level.
- Place Aeropress on jar and mount bottle on top.
- Fill bottle with remaining water and ice.
- When bottle is empty, disassemble and enjoy.
For a setup that's both easy and elegant, check out Yama's gorgeous wooden cold brew tower.
Choose Your Brew
Fierce loyalties aside, all iced coffee fanatics approach their favorite recipes the same way: we tinker and taste, mull and measure until conjuring that one magical brew, for which all vitality has been exhausted. (Thankfully, that’s when the caffeine kicks in.) We’re known for our fascination with detail and our obsession with precise methods and predictable results. And, to us, preparing coffee is no less of a craft when it’s served cold.
With taste as a trusty guide and the technical stuff for tips along the way, we believe that your favorite cup of iced coffee isn’t far off. Just like your hot brew, it can be fresh and flavorful, bright and bursting with the exotic characteristics of its origin. If you try one of the recipes we’ve recommended, or discover something special of your own, share it on Twitter by mentioning @primacoffee and including the unique hashtag "#icecoldcoffee". You can also leave your thoughts in the comment section below.
Here’s to keeping cool and caffeinated this summer.
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