If there is a spectrum of coffee beverage preparation, cold brewing is undoubtedly on the end furthest from espresso. Espresso extraction can take 24 seconds, cold brewing often takes 24 hours. Espresso typically has the lowest caffeine content per serving, cold brew boasts the highest. Espresso is volatile and often demands immediate consumption, while cold brew has a shelf stability that can exceed 1 week if refrigerated. Finally, the learning curve and equipment necessary for producing a palatable shot of espresso are the least accessible of all brew methods, while the skill and equipment needed for an acceptable cold brew are minimalistic and superbly approachable.
Regarding drinkability, cold brew can almost be considered 'thirst quenching', with its simple, sweet, chocolatey body and muted acidity. Critics of cold brewing rightly point out that it's not the best vehicle for aromatic nuance, but many claim to have developed palates that celebrate this expression, nonetheless.
'Cold brew' might have only recently become an American household term, but it commands a global and long-standing fan base. Devices for this style of preparation have been on the market since the middle of our last century, and many Asian coffee consumers have been familiar with this expression for decades.
Like any other method, there are a few guidelines to aid the home cold brewer. We see the same three categories here as we do in other 'hot brew' methods: consistent and proper grind, temperature and purity of water, and ratio of these two. The variables that determine the personality of your cold brew include: preference of room temperature extraction versus refrigerated extraction, total brew time (typically ranges from 6 to 24 hours), method of filtration, and preference for metered drip versus immersive (steeped). Honestly, there are too many variations for us to catalogue here, so we will focus on our two favorites—one metered drip and another that is immersive, both of which are easily done with rudimentary gear.
You do not need to invest in an elaborate Japanese contraption to experience metered drip cold brewing at home. All you need is:
- Coarsely ground coffee
- A measured bit of room temperature water
- Ice that you can either weigh or pre-measure as water before freezing
- A filter device
- A container (large enough to hold the ice) that will rest sturdily upside-down on top of the bed of coffee grounds
Set up your filter device with the grounds like you would for a pour-over (only with slightly coarser ground coffee). Instead of adding hot water to the grounds, pour your small amount of room temperature water into the grounds and stir it in to make a 'coffee paste'. You don't want to add enough to allow any water to flow through the filter, but you want all the grounds to be moistened. Then put your ice in the container and place it upside-down on top of the grounds. Obviously, the mouth of the bowl will need to be smaller in diameter than the filter device. Leave this out at room temperature to brew as all the ice melts into the grounds. The 'metering' is accomplished by the speed of the ice melting.
In our example below, we've repurposed the Pyrex glass from an old camping lantern. Take a look around your home or local thrift shop to find something that will work for you.
In order to do this, you might need to invest in a 'cold brew bag' which is basically a cotton sock that ties at the top. These can be found online and in local roasteries for around ten dollars. Other items you will need are:
- Coarsely ground coffee
- Measured room temperature water (from 15:1–17:1 water to coffee ratio)
- Some kind of pitcher or other large vessel
- Space in the fridge
Put the ground coffee in the bag. Hold it, still open, over the large pitcher. Pass half of your total water (at room temperature) through the ground coffee without allowing the grounds to overflow into the pitcher. Tie the bag closed, place it in the pitcher, and add the rest of the water. Put the pitcher in the fridge and let it sit for 24 hours before removing the bag. Immersion accomplished.
There are many ways to tweak these two categories and this is meant to be a place to start for those who are unfamiliar with the possibility of cold brewing at home. Even though the process takes a bit of time, the actual labor is about the same as making a single cup of hot coffee. The process is very scalable and since (as we mentioned before) cold brew is shelf stable when kept cold, there is no reason to not make a week's worth at a time and simply pour over ice as needed. The only limiting factors might be the size of your filter device, the size of your cold brew bag, or simply available fridge space. Keep brewing and keep opening your minds to the full spectrum of coffee craft.