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Coffee 101

America is a land of coffee lovers, whether we’re gulping down a quick cup or lingering over a barista-created drink.

More than 62% of Americans drink at least one cup of coffee a day, with the habit increasing its hold on the next generation.

So why not learn a bit more about what makes one cup different from another and how it can affect health?

A coffee tree produces coffee cherries, and the seed from that fruit is what we refer to as the coffee bean. They start out green and go through processing, drying and finally roasting to transform into a brown, aromatic “coffee bean” ready for the grinder.

Most coffee cherries contain two beans, but about 5% have just one. That lone bean is known as a peaberry, and some coffee mavens believe that peaberries have a superior flavor. During the early stages of processing, they may be sorted out to be sold separately.


About 70% of coffee grown commercially is Arabica, a species that originated in Ethiopia. It is grown in mountainous areas and tropical environments. There are many different varieties of Arabica coffee, but overall this species is less bitter and more flavorful than other beans.


The remainder of commercially grown coffee is Robusta, which is used for instant coffees and blends (If a package of coffee does not say 100% Arabica, it means some Robusta beans have been added to cut costs). It does not require the same climate or care as Arabica, and it produces a coffee that tastes more bitter and contains more caffeine.

When coffee was first introduced to Europe from Arabia, clergymen feared it and declared it to be “the bitter invention of Satan.”

Before roasting, green coffee beans are soft and smell like grass. The magic that happens in the roaster makes all the difference in how the coffee in your cup tastes.

Roasting machines operate at very high temperatures and keep the beans constantly circulating to avoid burning. During this heating process, the oil inside the beans is unlocked, and with it the aroma and flavor of the coffee we know emerges. Once the roasting process is done, the beans are immediately cooled.

A talented roaster is like a talented chef, understanding exactly when to stop the roasting process to get the desired flavor from the bean. The more time in the roaster, the darker the bean and the more oil released, all of which affects the richness and bitterness of the coffee.

  • Light Roasts have no oil on the surface of the bean and have a mild flavor
  • Medium Roasts are the most common in the U.S., with a balanced flavor between acidity and bitterness
  • Medium-Dark Roasts have some oil on the surface of the bean, giving them a stronger flavor and aroma, with a bittersweet taste
  • Dark Roasts produce beans that are shiny with surface oil and almost black in color. Think espresso. They have a fuller flavor, tasting a bit smoky and bitter (in a good way)

Contrary to expectations, the darker the roast, the lower the caffeine content.

For the best flavor, grinding fresh whole coffee beans just before use is recommended. Once coffee is ground, it starts losing flavor.


This process is not for the impatient. A percolator brews coffee when boiling water at the bottom of the pot rises up and passes through a basket of ground coffee at the top of the pot, over and over again, adding flavor to the water with each cycle.

Automatic drip

Since the 1970s, the automatic drip coffee machine has been standard kitchen equipment in the home and office. A reservoir holds water that gets heated and evenly distributed over ground coffee.

French press

This method is most popular in Europe. Ground coffee is placed in a carafe, and nearly boiling water is poured over it. After letting the coffee steep for a while, a small plunger with a mesh filter is pushed down through the water to keep the grounds separate as the coffee is poured. (Here is a detailed explanation of how a French press works.)

Cold brewed

Until recently, if you wanted iced coffee you took hot coffee and poured it over a lot of ice. That process dilutes the coffee as a good bit of the ice melts from the heat. The latest trend, cold-brewed coffee, eliminates the dilution problem by literally brewing coffee with cold water. Cold brews were taken a step further with the introduction of nitrogen infusion, pumping a bit of nitrogen gas into the brew to make the liquid richer and creamier – not to mention they have less acidity and bitterness than warm brews.

After the Boston Tea Party in 1773, American colonists switched from drinking tea to drinking coffee as an act of patriotism.

The latest research shows multiple benefits to regular coffee consumption, including lowering the risk for heart disease, type 2 diabetes, liver disease, Alzheimer’s and more.

Coffee contains small amounts of Vitamins B2, B5 and B3, manganese and potassium. It is also chock full of antioxidants, which help the body prevent cell damage.

While many previous concerns about coffee’s effect on health have been proven incorrect, there are some risks. Recent studies show that drinking more than three or four cups of coffee a day during pregnancy may lead to low birth weight, pre-term birth and even stillbirths. This may be because caffeine metabolizes more slowly in pregnant women.

Researchers who saw benefits in drinking coffee also warned that their findings apply to the coffee itself, not to cream, sugar and other things that might be added to it.

Coffee will stay warm longer if you put cream in it — making the liquid a bit thicker slows evaporation.

Coffee naturally contains caffeine, which stimulates the central nervous system and is mildly addictive.

An 8-ounce cup of coffee contains between 75-165 mg of caffeine, depending on variety, roast and other factors. Even decaffeinated coffee contains about 2 mg of caffeine per 8-ounce cup.

Caffeine is a stimulant, so many people stay away from consuming coffee later in the day to avoid disrupting their sleep.

Nancy Henderson

Nancy Henderson

Nancy Henderson, a writer and editor originally from New York, moved to Nashville more than 25 years ago and considers herself more Tennessean than Yankee these days. As Editor at Parthenon Publishing since 2005, she has written about health care and wellness for a variety of publications.

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