If anyone knows me, they know I spend almost 1/4 of my waking hours in a coffee shop or drinking coffee. I love the culture surrounding coffee, and the subtle complexity of its taste, which varies from one bean to another. There has been a lot of debate regarding the effects of coffee on health, from caffeine accelerating the onset of cardiovascular disease and raising blood pressure, to it causing heart attacks. I am about to embark on a discussion and research journey regarding this both amazing and intimidating compound and I hope you join me as well. Although I focus on caffeine from coffee, there is caffeine from various other sources, including other types of plants (Guarana, Yerba Mate), tea and energy drinks, but perhaps that will be a discussion for another time.
What is caffeine?
Caffeine is a chemical compound that stimulates our central nervous system. These compounds are found in coffee beans, seeds of the plant genus Coffea. As many of us know, there are many different species under this genus, including Coffea Arabica (from Ethiopia), and Coffea Robusta (Central Africa).
What does it take to cultivate coffea plants?
Environment
Generally speaking, Robusta is more lenient in environmental conditions. They can be grown at warmer temperatures, whereas Arabica requires colder temperatures, where the maturation season is during the coldest part of Autumn. Arabica prefers to be at high altitudes, and Robusta can be grown at much lower altitudes.
Coffea requires lots of water during its flowering phase, during which the beans are first harvested. The season with the least amount of rainfall denotes the second harvesting season.
Looking at the plant, I thought to myself, “Where’s the bean?”. The coffee bean is in fact not a true bean; it is actually the seed of a fruit, in this case a cherry. When the cherry turns red from green, it’s be ready to be picked. Here’s a cool video to get some visuals. The very outer layer of the cherry is the exocarp; next is the pulp, which is called mesocarp; this is followed by a pectin layer and a silver layer before reaching the bean itself. Most of the silver skin is is removed during the roasting process. A small amount remains in the slit where the coffee bean cracks during roasting; this is called the chaff and contributes to a significant portion of the bitter taste.
Roasting
Many coffee roasters that I visit tend to play with various roasting degrees, but mostly they hover around the first crack to second crack intensity. This gives a richer taste and the bitter flavour to our coffees.
Caffeine extraction
Coffee beans are ground, and then extracted usually using water and heat. The contact time between water and coffee affects the amount of caffeine extracted. Other factors include water temperature, size of the grind (the smaller the grind, the more caffeine is extracted), and roasting intensity. As such, espresso actually contains less caffeine than brewed coffee per average daily serving size, both because of the shorter contact time as well as the size of the beverage. A regular cup of espresso-based beverage contains about 1–2 oz of espresso, which amounts to roughly 60–100 mg caffeine. On the other hand, a regular cup of brewed coffee yields approximately 135 mg of caffeine.
Here are some values for you to get a sense of how much caffeine on average various brewing methods will extract.
Given the values above, how much coffee is too much coffee? In the second part of this series, we’ll dive into the nutritional impact of caffeine, and what the current research says.
References
coffeeresearch.org. 2016. The Optimal Coffee Environment: Best Climate Conditions for Growing Coffee Beans.[cited 2016–01–22]. Available from http://www.coffeeresearch.org/agriculture/environment.htm
National Coffee Association of USA Inc. 2016. What is Coffee? [cited 2016–01–22]. Available from http://www.ncausa.org/About-Coffee/What-is-Coffee
Health Canada. Caffeine in Foods — Food Additives. 2012–02–16[cited 2016–02–02]. Available From: http://www.hc-sc.gc.ca/fn-an/securit/addit/caf/food-caf-aliments-eng.php