The scientists first collected this raw material from a Portuguese coffee roasting company and dried it. Then they heated the powder in water at 163°C for 45 minutes, separated out the liquid, and added sugar. Next, the team mixed in yeast cells, let the concoction ferment, and concentrated the sample to get a higher alcohol content. (A similar process is used to produce other distilled beverages such as whiskey and rum from wheat and molasses.)
While the resulting booze has the flavor of coffee, almost all of the caffeine is removed during the brewing process, so while it might result in intoxiation, it will not result in stimulation. The abstract says, "Based on the sensory analysis, SCG spirit was considered as having features of a pleasant beverage, with smell and taste of coffee."