Bobby Finger

New York Times News Service

Around this time in July — when our ever-shortening spring weather takes a sharp right into the damp, hot depths of summer — coffee drinkers are confronted with a morning-altering decision: Switch to iced coffee to combat the oppressive weather, or commit to hot coffee as a kind of bold, unnecessarily masochistic act?

Those who prefer their summer over ice have also grown accustomed to another question: regular or cold brew?

If you’re unfamiliar with the difference, think of cold brew as traditional iced coffee’s unhurried fraternal twin. Cold brew can’t go a day without a long, luxurious bath, while iced coffee can barely swing a quick shower; cold brew has read “The Goldfinch” (and is planning on a reread before the movie is released later this summer), but iced coffee unfortunately never had the time — what with work and the kids — though it has seen the trailer on mute.

Once found primarily in the trendiest coffee shops and kitchens of adventurous home baristas, cold brew iced coffee has become a year-round staple. Chains like Starbucks and Dunkin’ have added the drink to their permanent menus. Cold brew makers like Rise, High Brew, La Colombe stock cans in major grocery stores. And at-home brewing kit companies have helped popularize DIY methods.

Rich Nieto, owner of Sweetleaf Coffee Roasters in the Brooklyn neighborhood of Greenpoint, said that cold brew has become so popular in recent years that it now outsells iced coffee in all but one of the company’s four locations. Still, even the most passionate cold-coffee drinkers have questions about their chosen beverage: Is there really less acid in cold brew? Will drinking it in the afternoon keep me up at night? Should I just make it at home? The good news is, we have answers.

What’s the difference between cold brew and iced coffee?

Both drinks are made from the same pair of magical, everyday ingredients — they’re just combined at different temperatures. Water heated to around 200 degrees Fahrenheit (about 93 degrees Celsius) and poured over the grounds will extract all of coffee’s most pleasurable essences in a matter of minutes. When cooled and poured over ice, you have a standard iced coffee. If the brewing water is room temperature, it must canoodle with the coffee grounds for much longer, anywhere from 12 to 24 hours, to produce a cup of joe worth sipping, but the resulting beverage contains coffee’s most sought after qualities — flavor and caffeine — without the bitterness found in one brewed hot.

Does cold brew coffee really have less acid?

My husband recently had an endoscopy that revealed an anomalous patch of tissue on the wall of his esophagus which had been exacerbating his acid reflux. His doctor informed us both that he should try to cut down on spicy food, alcohol and coffee. The first category would be easy, he assured me. The second? Achievable. But the third? Utterly impossible.

Dr. Rabia A. De Latour, a gastroenterologist and assistant professor of medicine at NYU Langone Health, said that it was a common sentiment, and that people who are “exquisitely sensitive” to caffeinated or acidic foods, and those suffering from gastroesophageal reflux disease, or GERD, would benefit from switching to cold brew if they cannot eliminate caffeine from their morning routine. “We recommend they cut out coffee completely,” said De Latour. But for everyone else, the difference between cold brew and iced coffee is negligible.

“I’ve seen this statistic a lot,” she said in reference to a oft-quoted claim that cold brew is 70% less acidic than regular iced coffee. “But I don’t see any scientific data to support this claim,” directing me to a study that shows “comparable” pH values from cold- and hot-brew samples, “ranging from 4.85 to 5.13.” For comparison’s sake, the stomach’s pH hovers somewhere between 1.5 and 3.5.

Does cold-brewed coffee have more caffeine?

Wading through the world of cold brew coffee can be a brutal game of trial and error. Thanks to the wide range of brewing methods, the difference in caffeine content among cold brews is considerably harder to predict than the amount of acid. After brewing for 20 hours, 16 ounces of cold brew at Starbucks contains 200 milligrams of caffeine (12 milligrams per ounce). While that’s about 20% higher than their iced coffee, which clocks in at 165 milligrams (10 milligrams per ounce), it’s considerably lower than the same amount of hot coffee, which has 310 milligrams (20 milligrams per ounce). Coffee from Dunkin’ reports similar numbers, with 10.8 milligrams in every ounce of cold brew.

But when you wade into more specialty waters, especially among prepackaged brands, the caffeine content is far from predictable. Canned cold brew brands Rise and High Brew have nearly identical packaging, but grabbing the wrong one could cost you. Rise’s original flavor contains 180 milligrams in its 7-ounce can (25 milligrams per ounce), which is anywhere from 30-50 milligrams more caffeine than what’s found in High Brew’s 8-ounce can. Stumptown, a roaster based in Portland, Oregon, sells cold brew in 10.5-ounce bottles that contain a whopping 29.4 milligrams of caffeine per ounce. To a caffeine addict like myself, that number sounds lovely. But to the uninitiated looking to give cold brew a shot, it’s a recipe for disaster.

“A lot of people will not tolerate that amount of caffeine,” De Latour said. “Some people’s GERD is worsened by coffee because of the caffeine content and its impact on the sphincter muscles,” adding that high amounts found in some cold brews can make people feel quite sick, with symptoms like jitters, peristalsis of the bowels, diarrhea, or even increased anxiety and stress. She then reminded me that it is, after all, a stimulant.

So that leaves us with cold brew prepared at home, a great option for those looking for more control when it comes to caffeine and acidity. The New York Times’ own recipe calls for just 12 hours of brewing. Similar recipes can be found across the internet, and all are easy to adjust in order to find the balance that works for your own stomach and pocketbook. A happy medium can be found in store-bought cold brew concentrates. These brews are meant to be diluted, so if you find it too strong, just add water or milk. Not strong enough? You get the idea.

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