Known to coffee cognoscenti since around the mid-2000s, the Ross Droplet Technique means adding a drop or two of water to beans just before grinding. The moisture reduces the static electricity built up during the grinding and leads to a tastier espresso. Upon noticing a similarity with what happens when volcanoes erupt, scientists in the US have further explained the technique by showing how adding water leads to a better extraction of the coffee’s flavour. “Moisture, whether it’s residual moisture inside the roasted coffee or external moisture added during grinding, is what dictates the amou…