Cold Brew and Nitro Brew
Not to be confused with iced coffee (in which espresso-based coffees are served over ice, usually with milk and syrup), cold brew coffee is simply coffee, brewed cold.
The coffee grounds are steeped in water for up to 24 hours to produce a concentrated coffee essence, which is then diluted to taste and served chilled.
Brewing cold results in the extraction of a range of flavor compounds, distinct from those associated with hot brews. Coffee geeks say the process highlights the characteristics of coffee beans from different origins that aren’t apparent in a traditional hot water brew.
Cold brew coffee is mellow, and sweeter than a conventional Americano or filter coffee, with a lower acidity. It's also a greener option, as it doesn't require heat or electricity.
Nitro coffee is already big in the US, and is created by adding nitrogen to cold brew coffee. The cold brew coffee is stored in kegs, then infused with nitrogen gas as it’s released through a pressurized valve with very small holes, which produces a cold, silky drink with a creamy head that is drunk black (it bears an uncanny resemblance to Guinness).
Nitrogen is a colorless, odorless gas that can be infused into a keg of cold brew coffee to yield a foamy, caffeinated beverage known as nitro cold brew. It's a totally new experience for coffee lovers, and has been gaining wild popularity in the specialty coffee industry.
Nitro cold brew has a gorgeous reverse cascade, so it's really cool to watch. The drink tastes creamy and fizzy -- some say it has the mouth feel of a Guinness beer (minus the alcohol taste, of course). Cold brew is smoother and less acidic and bitter than traditional iced coffee, and it's a little more caffeinated.