Sunday, January 22, 2006

Apple #142: Coffee

The subject of the chemical nature of coffee -- besides just the caffeine content -- has come up a few times in conversation the past couple of days. I don't drink coffee anymore because of the caffeine (even so-called decaffeinated coffee contains caffeine). Nonetheless, I'm taking it as a sign that I need to investigate coffee, in terms of its chemical make-up.

The majority of the information provided below comes from, a site maintained by the Coffee Research Institute, which goes far beyond typical marketing to provide lots of in-depth scientific information.

  • Researchers have documented over 800 different aromatic compounds present in one cup of coffee. Since some of the foods we like best are those with complex flavors or aromas (see my very first entry, on chocolate), it stands to reason that these 800+ compounds are a big part of the reason why so many people can't get enough coffee.
  • People have come up with one-word descriptions of some of those aromatic compounds, and here are some examples of the types of aromas one encounters as part of the coffee-drinking experience:
    • roasty (coffee)
    • catty-roasty
    • earthy
    • spicy
    • fruity, honey-like
    • buttery
    • sweet, potato-like
    • seasoning-like
    • roasty, walnut-like
    • cereal or cracker-like
    • toast-like
    • sweet, caramel-like
    • mushroom-like
  • In addition to the aromatic compounds are several different types of acids. Coffee-drinkers in Central America and East Africa prefer very acidic coffee, but if the coffee gets too acidic it tastes sour, and nobody likes that.
  • Here are some of the acids present in each cup of coffee:
    • Formic acid -- bees and ants produce this naturally, as do stinging nettles. It is primarily used as a preservative and antibacterial agent in livestock feed.
    • Acetic acid -- what gives vinegar its sour taste and sharp smell. It's used primarily as a solvent and is corrosive to many metals.
    • Lactic acid -- best known as the stuff that builds up in your muscles and makes them ache. It's produced by fermenting lactose, a milk sugar, and it is often used to tan leather and dye textiles.
    • Malic acid -- often referred to as the "apple acid" because it is often found in apples and other fruits. It plays a key role in the way living cells produce energy. Some people even take malic acid supplements to help boost their energy levels.
    • Phosphoric acid -- can be severely corrosive. If you ingested this by itself, you could get severe burns in your mouth, throat, and stomach, and you could even be killed. It is often used as a rust remover.
    • Quinic acid -- the acid most responsible for making coffee taste bitter. Its primary source is coffee beans, and it is beginning to be used in new pharmaceuticals, including Tamiflu, which has been developed to combat influenza.
    • Palmitic acid -- an amino / fatty acid. It is most often derived from vegetable fats and is often used industrially or in soaps as a lubricant or a softener.
    • Linoleic acid -- an omega-6 fatty acid, or the good kind of unsaturated fatty acid. People are attributing all sorts of healthy properties to this acid, including help in losing weight, easing of the symptoms of Alzheimer's, and bone loss prevention after menopause.
  • The concentration levels of these acids change the longer a pot of coffee is brewed, and the hotter it is allowed to get. Here's a breakdown of the way these acids change:
    • 1 minute: levels are relatively low, or baseline
    • 5 mintues: concentration levels rise considerably, even doubling in some cases
    • 14 minutes (how many people let their coffee brew for 14 minutes?): levels drop back down again, but not all the way to their 1-minute levels.
    • A similar bell-curve sort of fluctuation happens as the temperature continues to rise.
  • A third type of component in coffee is bitterness. Surprisingly, the bitterness helps to balance out the acidity, but again, it is important not to let the bitterness get out of hand.
  • The amount of bitterness that people taste is related mostly to the roasting and extraction process. Generally speaking, the more solids present in the cup, the more bitter it will taste. Here are some other tips to help reduce bitterness:
    • Use hot water as opposed to cold when brewing; this will release more of the aromatic compounds
    • Add sugar, salt, or citric acid (lemon juice, for example)
    • Medium-roast has a lower perceived bitterness than dark roast.
    • Caffeine has a distinctly bitter taste, but it is considered to contribute only about 10% of the coffee's overall bitter flavor. Decaffeinated coffee will generally taste less bitter.
    • A coarser grind may reduce bitterness, but be careful that you have the size that will work best with your brewing method, otherwise you might get big solids in your coffee, and that will jack up the bitterness again.


In other news, I have been enjoying taking the personality tests at OKCupid. It's pretty mindless, but entertaining. For those not familiar with OKCupid, the site makes all sorts of questionnaires available, and if you like, you can use the results of these questionnaires to find people with similar tastes and interests. I haven't used it for that purpose; I just like taking the tests. To facilitate this people-meeting business, the website also enables you to write your own test. After taking I don't know how many tests, I finally decided to try my hand at writing my own.

For those who have been tuning into this blog for quite some time, you might remember an entry I wrote on Charlie's Angels. For Christmas I received the DVD box set of the first season of this show and have been indulging myself on it recently with great glee. So it was that I decided the subject for my very own OKCupid test should be all about one of my all-time favorite TV shows.

So, if you like, you can try out my test, whose title reveals its very highly scientific importance, The Which Charlie's Angel Are You Test. You may want to bone up a little bit first, but I can't promise that my Apple gives away many of the "answers." Enjoy!

Coffee Research Institute, Coffee Chemistry - Aroma, Coffee Chemistry - Acidity, Coffee Chemistry - Bitterness
Wikipedia, Formic acid
Wikipedia, Acetic acid, Acetic acid, Lactic acid
PDR health, Malic acid
Material Safety Data Sheet, Phosphoric acid
Wikipedia, Phosphoric acid
Wikipedia, Quinic acid
Chemical land 21, Palmitic acid, Omega-6 (Linoleic acid, etc.)

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