CAFFEINE CONTROL

Managing the Speed of the Bean

by Jim Fadden

COFFEE MAKES PEOPLE HAPPY, excitable, anxious or able to leap tall buildings. Pick an effect and you are likely to find studies that both support and refute that effect. Although the effects of caffeine are under constant debate, there is no doubt that it is the world’s most popular drug—and, of course, the delivery vehicle of choice for many people is coffee. Short of renaming the profession of “roaster” to “dealer,” it is important for roasters to understand their contribution to the strength of their customer’s caffeine dose.

Consumption Variations

Like most substances, the influence of caffeine on the human mind and body is closely tied to the amount consumed. Variation in consumption is one cause of the conflicting results of scientific studies on the benefits or harmfulness of caffeine in coffee (see sidebar: Caffeine Consumption Conundrum). Caffeine content in a five-ounce cup of coffee can range from 60–175 milligrams. If packaging laws changed tomorrow, and required labels on roasted coffee showing caffeine content, how many roasters could provide this information?
    Obviously, the final caffeine content in a cup of coffee is impacted both by forces that are under control of the roaster and those that are not. At the extreme end of “not controlled by the roaster” is the case of a 27-year-old man who ingested more than a pound of ground coffee in an attempt to get “high,” which turned into a near lethal experience. In the realm of more typical consumption, brewing methods play a role, as well as the amount of coffee relative to the amount of water and the volume of milk or syrup in the cup. However, the starting content of caffeine in the beans is still impacted by choices made by the roaster.

Green Bean Selection

The biggest impact the roaster has in the final caffeine content is in the selection of green beans to be roasted. Although not typically roasted and sold as stand-alone specialty coffees, robusta is often added to espresso blends to add body and enhance the crema. It can also be used to create caffeine-boosted “high-speed” blends. Most publications refer to an average caffeine content for robusta of 2.0 percent by weight, however, according to the Research Center of the Coffee Board of India, the caffeine content of robusta varies greatly. It may contain caffeine in amounts as low as 1.16 percent to an eye-opening 4.0 percent by weight. Even given this range of concentrations, robusta on average will have much higher caffeine content than arabica. As caffeine is a natural anti-fungal, this also helps to explain robusta’s higher resistance to rot and disease.
    Within the world of arabica coffees the caffeine content also varies much more than the typically quoted 1.0 percent by weight. Again, according to the Research Center of the Coffee Board of India, arabica coffee contains anywhere from .58–1.89 percent caffeine by weight. The variation in the amount of caffeine is the result of many factors that have not been fully studied. There is variation between cultivars, such as bourbon and typica. There is variation according to altitude, with beans grown at higher altitudes having higher caffeine concentrations. Generational adaptations to micro-conditions, such as higher exposure to pests and fungus, also appear to increase caffeine content. All of these variables combine to make it difficult to generalize caffeine content of arabica coffees based on the country of origin.

Where’s the Caffeine?

In the future, there may also be another choice: an arabica coffee bean that lacks caffeine altogether. There are two possibilities currently under research, neither of which comes without controversy. There has been growing interest in a bean that has naturally reduced caffeine content and was originally discovered in Ethiopia and researched in Brazil. The enormous market potential of producing naturally grown decaf beans on a mass scale with the same flavor profiles as traditional arabica cultivars has led to a battle over the ownership rights of the plant stock under research.
    An even more controversial alternative involves the creation of a new type of coffee plant by genetically modifying the plant to eliminate the caffeine. Besides caffeine-laden Coffea arabica and Coffea canephora (robusta), there are several coffee varietals that are naturally caffeine-free but do not have a desirable flavor profile, such as Coffea salvatrix, Coffea eugenioides and Coffea bengalensis. All three of these varietals start with the materials necessary for caffeine, but two of the varietals (C. salvatrix and C. bengalensis) never develop caffeine and the third (C. eugenioides) develops caffeine temporarily but then breaks it down to other components. The current research is in identifying the genes in these varietals that either prevent the production of caffeine in the first place, or eliminate it after it is produced, and encode C. arabica with these genes. Because the long-term effects of human consumption of genetically modified foods have not been extensively studied, there remains much controversy over the future of genetically modified caffeine-free arabica coffee.

Caffeine Consumption Conundrum

YOU ARE WORKING a double shift and have been roasting coffee late into the night. You are cranky, your boss is a jerk and you are starting to lose your ability to concentrate. Loading, monitoring and dumping the beans isn’t too challenging, but paying attention to the details when dealing with expensive beans and potential fire hazards is important. A couple of cups of coffee seems like a good idea, a little pick-me-up to get you through the night. An hour later, you feel better, you like your boss again, your tasks seem easier, and you are able to roast and plan the next day’s deliveries at the same time. Some more coffee sounds like a good idea, so you drink another half of a pot.
    Fast forward another hour. The roaster is on fire, your boss is screaming at you and you can’t decide which problem to tackle first. Welcome to the world of the confounding effects of coffee and caffeine consumption.
    Caffeine holds off drowsiness in two ways: by stimulating the central nervous system and by blocking the chemical process that makes you feel tired.
    What happens is this: to make you sleepy, your body produces a chemical called adenosine, which binds itself to receptors in the brain and acts to slow down nerve cell activity. The reduced nerve cell activity creates the feeling of drowsiness.
    Caffeine works by binding itself to the receptors, thus preventing the adenosine from doing its job. The nerve cells, instead of slowing down, now speed up. This leads to that familiar feeling of increased energy and awareness that happens when we drink coffee. This is the desired response for many people: a feeling of more energy and the ability to concentrate on non-stimulating tasks.
    But if some coffee is good, isn’t more coffee better? Science tells us there is a limit where coffee actually starts to degrade performance, but that limit is difficult to predict on an individual basis. What complicates the situation from a scientific analysis point of view is the fact that humans tend to adapt to the effects of caffeine over time by producing more adenosine receptors in the brain. In habituated individuals, more caffeine is required to block the new receptors in an ongoing upward spiral.
    What makes the prediction of the effects of caffeine truly confusing, however, is that they cannot be isolated from other things in our environment that stimulate us. For example, a person who has had four cups of coffee may be able to concentrate better and longer on everyday tasks, like moving sacks of beans from one room to another. The same person, however, may not be able to deal as well with increased stress, such as a roaster fire, while under the influence of caffeine.     Caffeine and environmental stress tend to compound each other—a good thing when environmental stress is low, a bad thing when environmental stress is high. Once the body becomes over stimulated, it tends to shut down. This helps to explain the results of studies that show that larger doses of caffeine actually degrade performance on complex tasks, such as dealing with an irate boss.
    Individual responses to caffeine also depend on a host of other factors, such as genetics and interactions with other substances like nicotine. In addition, women respond differently than men, younger people respond differently than older people, and even personality may have an impact.
    Despite the contradictions in studies and effects, one thing is clear: the next time you go for that second round of coffee, it might be best to avoid irate bosses and roaster fires.

Roast Level

Beyond selection of the green beans, the roaster is commonly thought to control one more variable in the final caffeine content of the beans: the roast level. Popular lore has always been that the darker the roast level, the lower the caffeine content. This is not really the case, as caffeine changes very little during the roasting process. Caffeine has a very stable crystalline structure with a boiling point above 600 degrees Fahrenheit, far above roasting temperatures, which rarely exceed 470 degrees Fahrenheit. This means there is very little change to the caffeine during the roasting process. The minimal amount of caffeine lost during roasting is attributable to sublimation, which is the transition of a substance directly from its solid state to its gaseous state, as commonly occurs with dry ice. Caffeine undergoes this transition at around 350 degrees Fahrenheit. Since coffee is roasted at temperatures above 350 degrees, a minimal amount of the caffeine is lost this way during the roasting process.
    Although minimal caffeine is driven off or destroyed in the roasting process, the bean undergoes major changes during roasting. This can confuse the situation because the caffeine content per weight and per volume changes—not because the caffeine changes, but because the size and the weight of the bean changes. Ironically, because the bean loses weight (mostly water) during roasting, the caffeine content by weight increases, but because the bean increases in size during the roasting, the caffeine content by volume decreases.
    It is fortunate that there are no requirements to label caffeine content on packages of roasted beans. So many variables contribute to the caffeine content of a single origin at a defined roast level that it is nearly impossible to predict the content without decaffeinating the bean and measuring the amount extracted. Now take differing cultivars from multiple farms and multiple countries, throw in a little robusta for an espresso blend, and you might need to put on another pot of coffee and call an organic chemist.

SPECIAL THANKS to Ted Lingle and Joseph Rivera of the Specialty Coffee Association of America for their contributions to this article and to Gene Spiller, author of Caffeine.

JIM FADDEN is a mechanical engineer and frequent contributor to Roast Magazine.
He can be reached at jim@roastmagazine.com.