PODcast #39 : Espresso Pods News

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Espresso Elucidations

Bitter Irony — Without the Irony

Bitter coffee got you down? This month we look at bitterness in coffee and where it comes from. In essence, there are three places to look — the bean, the roast, and the extraction.

The first is a matter of choice. Robusta beans have more chlorogenic acid than Arabica beans, so it stands to reason that if avoidance of bitterness is of primary concern, then you might start your journey by choosing 100% Arabica pods. On the other end of the spectrum are pods heavy in Robusta, such as the Izzo Vivi and Covim Orocrema. The Robusta in these pods does contribute to bitterness, but it also contributes huge body, robustness, and crema.

Next in line is the roasting process. This can be a complex issue, but the short of it is that dark roasts are more bitter than light to medium roasts.

Chemists in Germany and the United States say they have identified the chemicals that appear to be largely responsible for bitterness in coffee. Their study, one of the most detailed chemical analyses of coffee bitterness to date, was presented at the 234th national meeting of the American Chemical Society.

"Everybody thinks that caffeine is the main bitter compound in coffee...," said study leader Thomas Hofmann, a professor of food chemistry and molecular sensory science at the Technical University of Munich in Germany, but just 15 percent of coffee's bitter taste comes from caffeine.

Hofmann and his colleagues found two classes of compounds that give coffee the bulk of its bitterness. Both are antioxidants found in roasted coffee beans, but not in the unroasted beans. (Note that they are antioxidants, which are healthful — but sadly untasty.)

One class, called chlorogenic acid lactones, is present at high levels in light- and medium-roast beans. Dark roasts showed high levels of phenylindanes, which form when the chlorogenic acid lactones break down and give a more lingering, harsh taste than their precursors, Hofmann said.

"Roasting is the key factor driving bitter taste in coffee beans. So the stronger you roast the coffee, the more harsh it tends to get," Hofmann says, adding that prolonged roasting triggers a cascade of chemical reactions that lead to the formation of the most intense bitter compounds.

Finally we have the brewing / extraction process as a culprit in bitterness. No mystery here — over-extraction increases bitterness. By continuing to pump hot water through the grounds, too much is extracted from the grounds. In addition to the desirable compounds, the bitter compounds are extracted in greater proportion. Remember, one pod = one ounce of espresso. If you are filling an entire 2 ounce demitasse with the extraction of one pod, you are pulling bitter compounds out of the coffee that should be left behind. Don't do that!

Some portions of this article are attributed to:
American Chemical Society (2007, August 22). Battling Bitter Coffee: Chemists Identify Roasting As The Main Culprit. ScienceDaily. Retrieved January 19, 2009, from
http://www.sciencedaily.com/releases/2007/08/070821143629.htm

Coffee News

Coffee Intake and Hallucinations

If you're drinking too much coffee, you might just be seeing dead people — at least according to the following study. This story has appeared in numerous websites, reporting on research work that links high intake of caffeine to halllucinations. The study suggests people who drink more than seven cups of coffee a day have an increased tendency to hallucinate. According to researchers from the University of Durham, high caffeine users may even think they sense non-existent people. These findings are the result of 219 self-report questionnaires by college students. Of course, besides coffee, caffeine can be obtained from sources such as tea and energy drinks, etc.

The study was based on the knowledge that the hormone cortisol, released in response to stressors, is understood to play a role in the development of psychotic experiences — and that caffeine intake increases cortisol release.

When under stress the body releases cortisol, which is produced in greater quantities after consuming caffeine, possibly leading to hallucinations. Seeing things that were not there, hearing voices and sensing the presence of dead people were among the experiences reported by participants. The ability of caffeine to exacerbate the effects of stress may be behind the study's findings, scientists believe. Those who had a high caffeine intake were three times more likely to have heard the voice of someone non-existent than "low" users who consumed less than one cup of instant coffee or its equivalent. "One interpretation may be that those students who were more prone to hallucinations used caffeine to help cope with their experiences," said Dr Charles Fernyhough, one of the study's co-authors.

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That's all for this issue of the PODcast.


Kevin Garrett, The PodMerchant.