Mar 16, 2018

Coffee Bean Types

The two species of coffee beans most widely cultivated commercially are Coffea arabica (Arabica) and Coffea canephora (Robusta).


The coffee that most are accustomed to is made from arabica beans which typically have better flavor. Arabica comprises about 75-80% of world production.

Estimates of caffeine content average about 1% for Arabica beans and 2% for Robusta beans by weight.

Starbucks advertises that it only uses arabica beans, Even though its coffee consistently is rated with higher caffeine than Dunkin Donuts, McDonalds, etc.

There are a number of techniques in brewing coffee: concentrate brewing, Turkish or Greek, vacuum brewing, percolating, the French press (also called press pot or plunger coffee), and drip or filter coffee. Assuming that the brewing method stays the same, the finer you grind coffee, the more caffeine it will release.

Temperature is also an important factor. Proper coffee extraction happens between 195-205 degrees, however most drip brewers only reach about 190 degrees. Espresso machines usually brew at near boiling temps. With French press coffee, you have total control over the temperature with the option of pouring boiling water (212 degrees) over the grounds. Water temperature can vary by brewing method, with the hotter the water, the better the extraction. With better extraction comes better tasting coffee and caffeine extraction.

Brewed coffee requires that the water is in contact with the grinds for a long time, this leads to a higher caffeine concentration. Espresso actually has the lowest caffeine content at 100 mg per 2 ounces. However, if you consider the amount of caffeine per ounce, espresso has more caffeine than drip coffee. Coffee brewed in the French press has 107.5 mg per 7 ounces. Drip brewed coffee is highest, with 145 mg of caffeine per 7 ounce cup. Generally, for brewed coffee, two tablespoons of ground coffee is used per 6 fluid ounces of water.

Light, medium, and dark flavors are an indicator of flavor strength, with the dark roasts having the boldest tastes. The darker the beans, the longer they have been roasted. The loss of caffeine from light to dark is minimal, regardless of what many web sites show.

Factors, in addition to brewing process that affects the amount of caffeine: variety of coffee bean, roast level, temperature of water, amount of coffee, brew time, grind level, and beverage size.

Bottom line - longer brewing time, fine ground, robusta equals more caffeine.
Shorter brewing time, course ground, arabica, (light, medium, or dark roast) equals less caffeine.

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