I’ve been saying it for the last year, that these days you can’t throw a rock without hitting someone who is making, selling or drinking cold brewed coffee! It is the drink this summer and for good reason: it’s awesome! The latest episode of I Brew My Own Coffee had a nice overview on all things cold and coffee from the Brians, and I wanted to get a little geeky with it myself.
My first personal experience involving coffee that I can remember, which happened sometime before the age of five, actually involved cold coffee. I remember being dragged along by my mom and her friend to go to garage sales in pre-1980 Ohio and I was thirsty (kids have it good these days with their snacks and their water bottles!). My mom offered me what was left of her cold Folger’s in a styrofoam cup. Not good.
So, that’s the first thing you need to know about cold coffee: brewing hot coffee and tossing it in the fridge or dumping it over ice is not what cold brew is all about.
The second thing you need to know is that just about anyone can make good cold brew at home with virtually no special equipment. You need water, a container of some kind, and some coffee. A filter is nice, too. 🙂
So, why the heck is cold brew or iced coffee so dang trendy right now? The answer is that it’s Summer for half of the world, and it’s hotter than heck and it’s a great drink. It’s fast, convenient, easy to make and, likely, profitable from the perspective of a cafe, too.
The Science
Water temperature is really, really important when it comes to brewing coffee. Around 195-205°F is the ideal range for most brewing methods. Remember, making a cup of coffee is chemistry and what we’re trying to do is dissolve solids (coffee, or rather, the stuff inside the coffee seeds) into a solvent (water). Get hotter than about 205°F and you’ll be pulling out some really bitter stuff that you don’t want, but (generally) going much cooler than the 190’s°F and you’ll be grabbing chemicals associated with sourness while simultaneously dissolving fewer sugars.
You’re probably wondering, then, how cold brew coffee, made with room temperature or ice water, can possibly result in something people actually want to drink? The answer is time and, still, temperature.
Water used for cold brew is either iced, right out of the tap, or the whole works is put in the fridge, so the water is much lower temperature than the range where those nasty sour/gone-bad compounds are extracted. Also, cold brew is made over a matter of hours (4-6 hours for a drip tower, 12-24 hours for full immersion methods), so all that time means you’re pulling as many of the sugars as possible out of the coffee. Yum!
The Results in the Cup
The results of cold brewing is low acidity, tons of body (downright syrupy!), lots of sweetness, a decent shelf life and the ability to make a concentrate that can be shaken with ice, diluted, etc. About the only negative is the acids conundrum: yes, cold brew is low-acid, but you want some of those acids in coffee to give it some high notes and some brightness. Cold brew can be on the flat side. The desirable acidity in coffee has a similar effect as squeezing some lemon on seafood, so when coffee doesn’t have that acidity it can be dull.
Some roasters/cafes like Oddly Correct in Kansas City have attempted to defeat this flatness by adding hops to their cold brew. Oddly’s Hop!Toddy has brightness added back in as the alpha acids from the hops infuse the cold brew. Here’s a BIG throwback to my old blog, The Liquid Diet, where I reviewed Oddly’s Hop!Toddy in 2012! It works great and there is a TON of experimentation you could do at home along these lines.
There are other ways to try to get some brightness into cold brewed coffee, too, and I’ll tell you about those, soon.
Traditional Cold Brew Methods – Full Immersion and Slow Drip
The most traditional form of cold brew and what I’m finding I prefer, is full immersion. It can be as simple as tossing grounds into a jar/jug/bucket/whatever and letting them sit for 12-24 hours. That’s what I do at home: mason jar, water and grounds and then I pour through a filter to clean my extract a day later.
I’ve heard people using nut milk bags (widely available for making almond milk and the like) and then they just pull the bags out and everything is already separated. You may have to play around with the type and manufacturer of these bags because lots of chemicals can get used in the processing of cotton and if these bags are sitting in your solvent (water) for 24 hours there is a lot of possibility of some nastiness leaching out of the bag. I haven’t used them myself so I can’t comment. The Toddy is an inexpensive, easy way of making larger cold brew batches, too. Filtering out the brew is pretty simple, from what I understand.
Another form of cold brew which is a bit more involved and certainly takes special equipment is the cold drip. Rather than immersing the grounds fully for 12-24 hours these methods usually do more of a 4-6 hour or so long brew by SLOOOOWLY dripping cold water through a column of ground coffee. I have had a Cold Bruer at home for almost two years and it’s a viable option for making small batches of cold dripped coffee. A lot of shops have one or more “Kyoto” brewers or cold brew towers set up to do basically the same thing. These are a lot more expensive and take up a ton of space, but look cool! You can also get pretty big ones for doing cafe-sized batches.
In my opinion, the tower/drip/Bruer methods produce a cleaner cup with less body and more brightness than the full immersion style. On the downside, my Cold Bruer takes more attention and fussing with than my mason jar method, which I just leave sitting on the counter for a day and never touch, and it also makes less coffee. If you need to, you can batch brew cold brew coffee in big food-safe plastic buckets to make gallons of this stuff at a time! You can’t do that easily with a dripper.
Hybrid Methods – Hot Blooms and Iced Coffee
A lot of people are experimenting with hot blooming their coffee, then doing a traditional cold brew. Blooming coffee means you add a small-ish amount of water to the grinds to get them all wet and then let them sit for a minute or so. Fresh coffee will bubble, burp and puff up, sometimes dramatically. The theory behind blooming coffee is that it extracts some good stuff while also promoting the off-gassing of some bad stuff, but like most things in coffee there is some discussion about whether it really matters.
For cold brew, though, you’re getting a little bit of both worlds: the hot bloom is extracting some of those acids that aren’t touched by colder water, so the idea is to do a short extraction with hot water, and then add the rest of the cold water like normal and let it sit just like you normally would. Bryan Schiele mentioned in episode 19 of I Brew My Own Coffee that he uses about 20% of the total water for his cold brew at 205°, blooms the coffee for about a minute, then adds the remaining 80% cold water and steeps for 12-24 hours. Lots of things to play with here and after I wrote this I did my own experiment of two identical cold brews side-by-side, one normal and the other with a hot bloom. I will report on my findings later in the week.
Another method that is very popular and that I do frequently is “Japanese iced coffee” or variations of it. This is hot-brewed coffee that is essentially flash cooled. You can use any pourover device or AeroPress for this one. What I do is replace 50% of the weight of water I would use for my pourover with ice cubes that I throw into the Hario server that I brew into. I then brew my coffee as I normally would, except I use 50% as much hot water. So, for example, if I’m using 30 grams of coffee, I would normally use 450g of water in the pourover. If I am making iced coffee, I put 225g of ice into my server, then I make a pourover that drips right onto the ice with the other 225g of 205°F water.
I will usually just decant into a glass and enjoy, but you can shake it in a cocktail shaker, too, which aerates the cold coffee a little and gives it some texture. This type of coffee is way better than just hot-brewing coffee and pouring into a glass of ice and I am not really sure why. My guess is that dripping the coffee right onto the ice while it brews limits oxidation more than brewing a full cup of hot coffee and dumping it onto ice, but that’s just a theory. Oxidized coffee gets sour and gross, so that would stand to reason that any process that limits oxidation would be a good thing.
Finally, there’s even an espresso version of this, where you can brew espresso, pour it into a shaker with ice and shake the ever-loving heck out of it. In Italy this is called a shakerato and they’re very common.
Coffee “Cocktails”
This is something I haven’t explored a whole lot, but I was turned onto the idea by the good folks at Dapper & Wise on my last trip to Portland in the spring. I got into a chat with the barista and manager and they said they have two popular drinks involving espresso. One was pouring espresso into a glass of ice and Mexican Coca-Cola (pretty good, for me brings out lots and lots of caramel flavors from the Coke) and the other is the same thing over tonic water. The quinine in the tonic gives some acidity and dimension and sort of a citrus vibe. Both are fine and I enjoyed both when I played around with combinations at home. I tend to be a bit of a purist when it comes to espresso, though, so I’d just as soon have an espresso, and then a glass of Coke or whatever instead of mixing them together. The one exception, however, is affogato…
Affogato: The King of All Things Holy
Affogato is an Italian dessert wherein you pour espresso into a bowl of ice cream. I actually just extract the espresso straight into my bowl when I do this at home! For being as big of an ice cream fan as I am a coffee geek I have been surprisingly tame with this dessert and have only ever used straight vanilla, but you can really get crazy with this using different flavors of ice cream and, of course, different origins and blends of espresso, too.
Affogato is better than any coffee ice cream you have ever had, period and end of story. My wife hates coffee and loves when I make affogato.