The coffee world is a chock full of trends, and the hottest one to hit cafés recently is the phenomenon known as nitro (short for “nitrogenated”) coffee—cold coffee “on tap” or “on nitro” that has been infused with nitrogen. Nitro coffee is also commonly called Nitro cold brew or Nitro cold press. The effect is a frothier drink with a thicker, more pleasing texture in the mouth, and popularity is soaring: Esquire listed nitro coffee among its “Best of 2015” drinks.
Nitro coffee was invented in 2013 by Nate Armbrust, a food scientist from Portland, OR, who decided to explore ways to make his cold brew coffee tastier. The process involves adding tiny nitrogen bubbles to the brew by squeezing it through a special tap fitted with a restrictor plate. Armbrust found that the response he got from tasters was overwhelmingly positive, and he moved forward with his new beverage.
The idea of nitrogenating is borrowed from brewers of beer, who have long been adding either carbon dioxide or nitrogen to their brews for that classic fizz. Typically, CO2 is the choice of brewmasters for the majority of beers (Hefeweisens, lagers, IPAs and the like), preferring nitrogen gas mainly for smoother or sweeter brews (some stouts and dark ales) due to its consistency. Since coffee is so often enhanced by smooth and sweet additives—think cream and sugar—the nitro experiment makes perfect sense.
The Chemistry Behind Nitro Coffee
Perhaps the biggest reason nitrogen, as opposed to carbon dioxide, plays well with coffee is acidity; carbon dioxide adds it, while nitrogen doesn’t. Armbrust first experimented with adding CO2 to his brew, but recognized immediately he was on the wrong track. “Coffee just doesn’t take acid the way juice or teas can,” he said. “When the CO2 becomes carbonic acid in solution, it just destroys the flavor.” He next tried nitrogen, and the rest is modern history.