Tested: Cold- or Hot-Brewed Iced Coffee

Four years ago, I learned about cold-brewing iced coffee. According to the story in the New York Times, cold-brewed coffee would taste completely different than hot coffee that was then chilled.

“Without the bitterness produced by hot water, the cold-brewed coffee had hints of chocolate, even caramel,” the author wrote.

I was curious to try cold-brewed coffee, and even printed out the recipe, but never got around to it. When Harold McGee, the Times’ food/science columnist, wrote about the differences between cold- and hot-brewing earlier this week, I knew I needed to try out the different brewing methods myself.

I wanted to do this as scientifically as possible, but not tax myself (or my wallet) too much. There are a variety of specialty cold-brew systems that promise superior coffee. I wanted to know how the simplest cold-brewing method – combining ground coffee and cool water and letting it sit for 12 hours – would taste.

Water and coffee grounds after brewing together overnight.

My typical coffee brew strength is 20 grams of coffee and 12 ounces of water. That happened to be the recommended ratio for cold-brewed coffee. I brewed two identical cups of coffee – one with hot water in my automatic coffee pot, one with cool water sitting at room temperature in a water glass overnight.

The next morning I filtered the cold-brewed coffee, popped it into the refrigerator for a couple hours, and paid a visit to Starbucks to purchase a control iced coffee.

Here’s how I set up my tasting experiment: I wanted to know how the three varieties of iced coffee tasted black, and with milk and sugar.

I poured each coffee into a glass I had marked on the bottom. Then I mixed up the glasses so I wouldn’t know which one was which. This was as close to a double-blind study as I could get while serving as both the experimenter and subject. I tasted each coffee (making sure to munch on a palate cleanser in between) and made notes, then ranked them.

The results?

The home hot-brewed and then chilled coffee was my favorite, followed by the Starbucks control. The cold-brewed coffee was my least favorite. I could taste the difference between the Starbucks brew and the two home-brewed coffees (due to the different beans and roasts). I preferred the “wrong” coffee, however. In my tasting notes I wrote that the hot-brewed iced coffee was “the least bitter and most mellow,” while also being “bright.” The qualities usually attributed to cold-brewed coffee I was tasting in the hot-brewed cup.

On to part II of the experiment. I never drink iced coffee black, so of course I wanted to see how milk and sugar changed the tastes of the iced coffees. I made a batch of simple syrup, then added 2 tablespoons of whole milk and 2 teaspoons of syrup to each coffee. I put out fresh Post-It notes, re-shuffled the glasses, and tasted again.

The results?

My ranking stayed the same, with the hot-brewed iced coffee the best, the Starbucks control in the middle, and the cold-brewed iced coffee the worst. Score one for consistency!

While the three coffees tasted pretty similar in black form, after adding sugar and milk I had a clear least favorite. In my tasting notes I wrote that one coffee (which turned out to be the cold-brewed cup) had a “bad aftertaste that lingers.” My favorite version had “a balanced coffee flavor.”

What conclusions can I draw from this test? On this day, with this type of coffee (a medium roasted arabica bean from Colombia) cold-brewing coffee definitely didn’t perform well. I have no doubt that it’s possible for cold-brewed coffee to taste better, but I think special equipment is required to get the desired results.

It might not be elegant, but I’ll stick to popping my hot coffee in the fridge when I want an afternoon pick-me-up.

  • http://www.troubadourcoffee.com Wholesale Coffee

    Yeah I think cold brewed is the best, no bitterness.  I use a blend with Nicaraguan coffee in it and the chocolaty-cocoa notes are the bomb!

  • Lily

    Great post!!! Reminds me of our vodka test…memories! 

    I have to disagree with the results though.  We started to use the Toddy system (it was a wedding gift) and personally I like it better in the summer, mostly because it’s delicious and so easy to make ice coffee in the morning.  We make one big batch and it lasts 2 weeks. 

    I think the trick is cold brewing produces a “coffee concentrate”, which tastes good with diluted with ice and milk.  Whereas hot-brew coffee always tastes too watered down with ice in it.  We’ve also tried making coffee ice cubes with leftover coffee but my favorite way is still the cold-brew. 

  • Amul Kumar

    Personally, I think the problem you had is choosing to use a medium roast. I prefer making cold brew coffee (using the method you do, a basic overnight-in-water thing) using lighter roasted coffees. I’m looking for something light and summery anyway. The fineness of the grind is also pretty important – I’ve used ultra-fine expresso ground to get a gallon of cold press in about 6 hours. With a medium coffee grind, the difference between 11 or 13 hours is pretty minimal. With the expresso, the difference between 30 minutes of filtering time was pretty obvious.

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