by David Prosser

It has been a buzz-word since mid-2015 and hasn’t stopped spreading through the world like wildfire. It’s “cold-brew coffee,” an inky black concoction that is infinitely more flavorful than ordinary iced coffee. In case you were wondering, iced and cold-brew coffee are not the same, because cold-brew coffee undergoes a different brewing process to make it taste exquisite.

Cold-brew vs. Hot-brew Coffee

Sure, you might rely heavily on your at-home espresso maker to get the morning done right, but does that piping hot espresso really taste all that great? Probably not. The bitterness of espresso and other similar roasts can make lips curl if not properly sweetened to taste.

Though cold and hot-brews come from the same ingredients—coffee grounds and water—the flavor profile is completely different. Drinkers report that these two beverages look, smell, taste, and feel different. All this comes together to create that lasting impression with every sip.

But while the difference may be obvious, it doesn’t answer the question about why hot-brew coffee is slightly bitter and acidic, while cold-brew is sweet, aromatic, and chocolatey. The dividing line is found within the chemistry of the coffee.

The Grounds

Coffee grounds are comprised of certain oils, depending greatly on the roast (light to dark), chemical compounds, and acids. These soluble components get extracted from the grounds during the brewing process.

There are basically two brewing processes that most people are aware of:
1. Hot-Brewed Drip Coffee; and
2. Cold-Brewed Coffee

Hot-brewed Coffee

This is generally what people think of when they hear “coffee.” As for the image that pops up in one’s head, it is often of a coffee shop with percolating pots, syrup dispensers, and blenders. Or, there is the filter method done by pouring hot water over grounds and letting the water drip through to the cup.

Hot-brewed drip coffee takes mere minutes to make, leaving the aroma strong and the taste acidic or sour (or both). Hot water also pulls the soluble chemicals from the coffee grounds more easily, giving it that scent everyone goes crazy over.

However, this isn’t always a good thing. Because boiling water can change the chemical profile of certain materials, it can degrade and oxide the coffee’s chemicals, making it sour and bitter.

Cold-brewed Coffee

On the other hand, cold-brew coffee is prepared by taking coffee grounds and water at room temperature or cooler, and steeping said grounds for hours or even days. Then the coffee is strained from the grounds to finish the product. Because cold-brew coffee takes longer to brew, it has a more elegant flavor profile that is less acidic than the conventional hot pour.

Sure, degradation and oxidation still happen during cold-brewing, but not as fast. Plus, cold-brew coffee stays fresher for longer—lasting 2-4 weeks if refrigerated.

Cold-brew is certainly more palatable than hot-brew (and even diluted iced coffee), because the cooler temperatures do not destroy the aromatic compounds. However, cold-brew coffee also has less of that hot coffee fragrance.

So, simply put, the reason why cold-brewed coffee is so delightful is because of the chemistry of the brewing method. Next time you’re craving a cup of java, either hot or cold, think about the reason why the flavors are produced the way they are—and maybe try slowing down that hot-brewed drip by hand pouring! Or just beat the heat with some splendid homemade cold-brew.

David Prosser has been a product tester for a well-known US retail chain for half a dozen years; during that time he has laid hands on more products than most people buy in their entire life. Now he uses the analytical skills he’s learned to create awesome reviews with the team of writers over at bestpatrols.com.