I just drink it for the taste

So you are probably saying to yourself, "hey, I drink a lot of coffee, but am I really getting all of the caffeine that I need?" Well, here's some information from The Atlantic's new Food Section that may be of use to you:

In a couple of studies testing 90 different Arabica cultivars, the caffeine content varied between 0.42 and 2.9%. My morning cup would then vary between 84 and 580 milligrams, depending on which of these varieties was in my cup.

If your morning cup came from a commercial roaster who included Robusta in the blend, we have another level of complexity. Caffeine content in these coffees, in one study, varied between 1.16 and 4.0%. A straight 12 oz. cup, using 20 grams of the 4% coffee, probably wouldn't taste very good, but would definitely provide more buzz: 800 milligrams of caffeine.

As with most things, the more one learns, the more complex a topic becomes and, in a sense, the less one knows. To attempt accurate generalization:

• Arabica averages about half the caffeine as Robusta.
• The cultivar determines the caffeine content.
• Degree of roast has no meaningful effect on caffeine.
• An espresso made from 100% Arabica, on average, has about 70 milligrams of caffeine per shot; a 12 oz. cup of drip coffee made my way in a press pot, using two scoops of coffee per 12-ounce cup -- would have 200 milligrams.

Beware of taking this information very far, because individual responses to caffeine differ widely. Caffeine is metabolized faster by men and slowest by pregnant women. Body weight and eating will affect caffeine absorption.

Is there anything coffee can't do?

Narasimharao Kondamudi, Susanta Mohapatra and Manoranjan Misra of the University of Nevada at Reno have been doing research into whether used coffee grounds can be used to create diesel fuel.

If you look closely at your cup of fresh coffee, you may notice a thin film of oil on the top. Looks like there's more where that came from.

From the last issue of The Economist:

Dr Misra says that a litre of biodiesel requires 5-7kg of coffee grounds, depending on the oil content of the coffee in question. In their laboratory his team has set up a one-gallon-a-day production facility, which uses between 19kg and 26kg of coffee grounds. The biofuel should cost about $1 per gallon to make in a medium-sized installation, the researchers estimate.

Commercial production could be carried out by a company that collected coffee grounds from big coffee-chains and cafeterias. There is plenty available: according to a report by the United States Department of Agriculture, more than 7m tonnes of coffee are consumed every year, which the researchers estimate could produce some 340m gallons of biodiesel.

(Illustration by Pelle Mellor)