- "The removal of caffeine from beverages has plagued bartenders and restauranteurs for centuries! You can't expect me to solve it overnight!"
Caffeine (C8H10N4O2) is a stimulant that was present in a variety of foods and beverages, including coffee and raktajino, though a form of decaffeinated coffee did exist. (VOY: "11:59") It could be somewhat addictive to most humanoids if consumed on a regular basis (excluding Vulcans, according to T'Pol). (ENT: "Breaking the Ice") For centuries, bartenders and manufacturers tried unsuccessfully to create a suitable substitute. (DS9: "Nor the Battle to the Strong")
In 2153, when Enterprise NX-01 suffered heavy damage to its armory, Lieutenant Malcolm Reed drank black coffee instead of consuming his usual tea and crumpets, stating that he could use all the caffeine he could get. (ENT: "Proving Ground")
In 2370, a spectroscopic analysis of the liquid in Miles O'Brien's cup found vegetable-based oils and caffeine, leading Keiko O'Brien to conclude that it was in fact coffee he was drinking in a video clip. (DS9: "Armageddon Game")
As of the 24th century, there was yet to be a decaffeinated raktajino with a decent taste. Quark's attempt to create such a beverage for Major Kira during her pregnancy with Miles and Keiko O'Brien's son failed miserably. Had he succeeded, the new concoction would have been called "Quarktajino". (DS9: "Nor the Battle to the Strong")
In 2375, after seeing Kathryn Janeway drink a large amount of coffee, Neelix suggested that he ask The Doctor to prepare a hypospray instead so she could absorb the caffeine more directly. Janeway took the hint and decided to stop after her current cupful. (VOY: "Think Tank")