tell me more about cold brew coffee

Cold brew is different. It’s cold. Typically more concentrated. With a less acidic mouthfeel. It tastes a bit sweeter. Ever wonder why that all is? No? Want to read on anyway? Cool. 

Cold Brew, or Brewing with Cold Water

It seems like a funny thing to have to acknowledge, but at its core, cold brew is brewing with cold water. There are lots of ways to brew cold brew (check out the section on cold drip for how we brew it!), and all of them share one thing in common: brewed with cold water. Cold water makes a meaningful impact on how a coffee brews, that has a lot to do with how cold brews tend to taste. Maybe you come with a few preconceptions about what cold brew is - we definitely did before we started this project - but read on and hear our perspective (a good one, we think) about what makes cold brew... cold brew. Cold brew and iced coffee might both be cold, but are totally different! When we say cold brew, we’re talking about coffee brewed with cold water (check out the next section). This brewing approach brews a coffee with certain characteristics (again, well explain more below). And even though they’re both “coffee,” these will taste fundamentally different than iced or flash-chilled coffees, which are coffees brewed hot and then cooled down. We’re not saying that these aren’t good drinks - to each their own! - but they are a very different beast than a cold brew coffee.

So You Say Cold But You Mean...

Ready to have your mind blown? Many of the cafes that brew your favorite cold brew do so at room temperature. When we say cold water, what we really mean here is “not hot.” Ice cold water does behave differently than room temperature water (for instance, the viscosity is twice as high with ice cold water), but room temperature is still a wide difference from near-boiling water that your typical hot coffee is brewed with.

The biggest difference that you’ll note brewing with any cold brew style is that it takes much longer.  This is a factor of how the water interacts with the ground coffee - much more slowly. Brewing with hot water means that solubles are extracted faster. This comes from two different factors: certain compounds in the coffee are easy to extract at higher temperatures, and certain chemical reactions that take place are accelerated. All of these compounds are still extractable with cold water, it just happens more slowly, and at different rates. This difference in rates is what leads to a different tasting coffee - because certain compounds are under or over extracted compared to hot coffee, the final beverage will also taste different. 

Because of this lower efficiency, there is a point at which cold brew stops extracting. This means that for most immersion cold brews (where you soak coffee beans in water), the difference between brewing for 12 hours and 24 hours makes little actual difference in the final chemical makeup of the coffee. There’s been some really good recent research on how cold brew develops over the course of the brew process, and to put it mildly, lots of folks might be brewing much longer than they need to.

And We’re Left With What?

A cold coffee! The typical cold brew coffee is a bit of a misnomer, for the same reason that we don’t talk about hot coffee as a single concept (your barista would like a word with you about the difference between french press and a pour over). Still, there are some generalizable characteristics that we can observe with most cold brews.

Cold brew tends to have a much lower perceived acidity. Perceived is the operative word here, because when compared to hot coffee (look, now we’re lumping it all together), cold brew has a similar pH level. Instead, it’s the combination of dissolved solubles from the coffee bean that combine to give you the sense of an acidic coffee, and your typical cold brew has less of those. We’ve met dozens of people that swear by cold brew, with stomachs that are too bothered by hot coffee to drink it any other way.

Cold brew tends to be sweeter - again, the sweeter solubles that are extracted are more noticeable in your average cup of cold brew. Cold brew also tends to be brewed in concentrated form. It’s not that you can’t brew a hot coffee concentrate, but that it’s much easier for cold brew to be brewed in concentrated form without over or under extracting the coffee. Your typical cold brew tends to be 1.5x more concentrated than the standard hot coffee, but with styles like cold drip (again, how we brew!), you can easily up the extraction to 3x, 4x, and 5x higher than hot coffee. Up to you if you drink it straight or dilute it down, but it’s more typical that you’ll find it in the concentrated form.

Another benefit here is that you can keep it in the fridge for a few days and drink it as you please! Whereas no one wants to drink hot coffee a few days later, a cold brew can hold for 3-5 days without losing much flavor (and we’d be lying if we told you that we hadn’t drank week-old cold brew tucked away in the back of our fridge). Because of this, most cold brew devices are set up to brew in batches. Rather than spending considerable time brewing a cup, you can make enough for a few days, all at once.

One huge misnomer you might hear from cold brew critics is that cold brew has to be flat, with muted flavors. We hear this from a lot of folks who look at cold brew as a monolith, and it’s true that brewing immersion cold brew tends to miss out on the bright flavors that make a good cup of hot coffee so exciting. And this, dear friends, is where cold drip shines. Check out the next section to learn more.