The Hungarian mathematician Alfréd Rényi once said, “A mathematician is a device for turning coffee into theorems.” Usually tea is my hot caffeinated beverage of choice, but lately I’ve been craving coffee. Perhaps this is due to the frigid temperatures in my apartment.
Yesterday I decided to start an experiment with cold brew coffee. I’ve been seeing a lot of cold brew for sale lately, and apparently a lot of coffee connoisseurs are excited about it. In the cold brew process, coffee grounds are steeped for an extended period of time at room-temperature. At lower temperatures, many of the less-soluable chemicals in regular coffee don’t dissolve, so the cold brew has a different flavor profile.
For my first attempt at cold brew, I used a 1:10 ratio of coarsely ground coffee to water: 100g of coarsely ground coffee in 1 liter of water. I let the mixture sit in my chilly (55 degree) apartment for almost 24 hours before filtering it through a coffee filter and bottling it. The result was about 750ml of concentrated coffee – just enough to fill an empty liquor bottle.
To serve the coffee, I mixed about equal parts cold brew (gently heated), boiling water and scalded milk. The result was what I thought to be a fairly faithful representation of café au lait, but the flavor is definitely smoother, less acidic and a bit nuttier. Overall, I’d consider the experiment a success and I look forward to trying other drinks with my cold brew. I may consider making it more concentrated next time so that I can use more boiling water. That way I won’t need to heat the cold brew at all to get a suitably hot beverage.