The layered caffe latte is n’t the most wide known espresso drink on coffee - shop menus , but it is a scientific curiosity . Instead of a traditional latte , where steamed Milk River is poured into a shot ( or several ) of espresso , the superimposed caffe latte is made by pouring the espresso into a methamphetamine of hot milk . The final result is anInstagram - friendlydrink that sport a gradient of milky coffee people of color from pure white on the bottom to glum John Brown on the top . The effect is odd enough that Princeton University researchers settle to search the smooth dynamics that make it happen , asThe New York Timesreports .
In a new study inNature Communications , Princeton engineering professor Howard Stone and his squad research just what creates the discrete horizontal layers convention of superimposed latte . To happen out , they injected warm , dyed water supply into a tankful filled with warm Strategic Arms Limitation Talks urine , mimicking the process of pouring low - density espresso into higher - density roiled milk .
concord to the written report , the layered feel of the latte forms over the course of minutes , and can last for " tens of minutes , or even several hours " if the drink is n’t excite . When the espresso - like dye water was inject into the salt seawater , the down spirt of the dye water floated up to the top of the cooler , because the floaty force of the low - denseness liquid encountering the in high spirits - density seawater force it upward . The layers become more visible when the hot drink cool down .
The New York Timesexplains it succinctly :
This structure can hold up gentle move , such as a light inspiration or sipping , and can detain stable for as long as a daylight or more . The layers do n’t evaporate until the liquid cool down down to elbow room temperature .
But before you go trying to try out with layer your own lattes , know that it can be slippery than the study — which refers to the process as " at random pouring espresso into a crank of warm milk"—makes it sound . You may need to try out several time with the f number and elevation of your pour and the ratio of espresso to Milk River before you get the look just correct .
[ h / tThe New York Times ]
