The Great Debate: Does Espresso or Drip Coffee Have More Caffeine?
Espresso has gained a reputation for a lot of things, chief among them being that it's packed with caffeine and kind of snobby. While one of those is a matter of opinion, the other has been settled. Rarely for a coffee myth, the common wisdom that espresso has a higher caffeine content than drip coffee is actually true, though only if you look at it from a certain perspective. To solve the caffeine conundrum, it's best to look at how the process of making espresso is different from that of making drip coffee.
Starting where a cup of coffee always starts, with the grind, beans destined to be made into espresso need to be ground much finer than those used in drip coffee makers, since espresso makers use highly pressurized water that would shoot straight through coarser grounds. When hot water hits a batch of coffee grounds, it extracts oils and caffeine from it. The more total surface area the grounds have, the more of their caffeinated goodness they can let out, and since finely ground beans win in that regard, espresso has the advantage.
Time and Temperature
Adding water is the next step, and there are two ways that water affects extraction. Starting with temperature, hot water extracts better than cold water. Espresso machines tend to keep water hotter than drip coffee machines, meaning they again can pull more caffeine from the grounds.
Time also plays a part, as the longer the grounds stay in contact with water, the more caffeine they'll add to it. Here's where drip coffee brewers, and immersion methods such as french press coffee makers, have the advantage. The optimal brewing time for espresso is around 22 seconds, while making coffee with a drip brewer usually takes anywhere from three to six minutes.
By the Numbers
That's two points for espresso and one point for drip coffee, for those keeping score at home. So when it comes down to it, which method really produces the most caffeinated cup? Coffee Chemistry crunched the numbers to find out, showing that 1 ounce of espresso contains anywhere from 30 to 50 milligrams of caffeine, while 1 ounce of drip coffee holds between 8 and 15 milligrams.
Case closed? Not quite. While it's true that espresso has more caffeine per volume, what most people really want to know is what they should order to get the most bang for their buck. In that contest, drip coffee is the winner. While an ounce of espresso could constitute a full serving, people tend to drink their coffee in doses of anywhere from 8 to 24 ounces at a time. With that in mind, even a modest cup of coffee has more caffeine than a shot of espresso, while the oversized cups that some people prefer could have up to 12 times the amount.