Flash Brew vs. Cold Brew: What's the Difference?

They're both prime for summer days, but which should you go for? Get the basics on these brews—just in time for warm weather.
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When the sun's out and the humidity's high, the last thing you need is a steaming cup of joe to make you hotter. Enter iced coffee: the best way to wake up your mind without waking up the sweat glands. 

Making iced coffee isn't as simple as dumping a hot pot of coffee over ice. Various methods have been honed to create a non-watered-down, flavorful brew. But what are the methods, and how do they affect the coffee's flavor?  

We broke down two popular ones—cold brewing and Japanese-style flash brewing—to help you get the basics on the brews and pick the right method for you. 

Cold Brew

You can find cold brews everywhere these days, with various brands' bottled brews lining grocery store aisles (Stumptown, Starbucks, and Chameleon, to name a few). But how, exactly, is cold brew made, and why do people love it?

Cold brew is just what it sounds like—coffee brewed using cold water. There are a couple ways to do this, both of which take a good bit of time since cold water extracts coffee's flavor slowly. The most well-known cold brew method is letting grounds steep in cold water for 12 to 24 hours, then filtering them out. Pretty much anyone can do this method so long as they have a container to soak grounds in. Another slightly quicker but less accessible method is slow-drip. Slow-drip requires you to have a special instrument that releases cold water drop by drop onto coffee grounds, where the flavor is slowly absorbed and then released into a drainage container. This method takes around 6 to 12 hours. 

Regardless of which method you use, you'll end up with a smooth brew lacking in the acidity and bitterness traditionally associated with coffee. The oils in coffee that cause bitterness are released in hot water, not cold water. Without those bitter flavors, the coffee tastes sweeter, and the lack of acidity on the tongue allows the drinker to taste more of a coffee's flavors. You more easily pick up on those chocolate undertones and hints of fruit that drew you to the coffee in the first place.

Flash Brew

Flash brewing is pretty much the exact opposite of cold brewing. It's quick (hence the term "flash"), it's done with hot water, and the final product does retain coffee's usual bittersweet flavor. 

Flash brewing has been around for a while—it originated in Japan in the 1960s—but it's only recently begun popping up in grocery stores. (Boss Coffee, the third best-selling beverage in Japan, recently introduced its canned flash brew to the U.S., joining brands like Verve Coffee Roasters and Elemental Beverage Co.)

Flash brewing uses the pour over method. Hot water is poured over coffee grounds and  immediately drained into a container of ice, instantly chilling the coffee. To compensate for ice melt, coffee is brewed with less water. Because hot water does release coffee's oils, the final brew has coffee's classic bitterness, acidity and aromas. The entire process takes minutes—just enough time to boil water and set up your pour over. 

So which brew is right for you? Depends on what you like in your joe! If you drink coffee as a chore—something to keep you awake—but grimace when its bitter flavor hits, cold brew could be your new best friend. But if what you love about coffee is its acidity and nuance, flash brewing will give you those same hot coffee flavors in iced coffee form. 

Which brew do you prefer? Let us know!