KitchenAid KES2102 Tips for Great Results, What is espresso?, Overextraction and underextraction

TIPS FOR GREAT RESULTS

What is espresso?

Espresso began as an attempt in the 1800s to quickly brew coffee on demand, by the cup. The goal was to serve the freshest, most flavorful coffee possible and avoid the burned, stale taste of coffee kept warm on a stovetop. To speed the brewing process, coffee pioneers struck upon the idea of forcing water through the grounds under pressure. Steam was initially used to supply the pressure, followed by compressed air, lever operated pistons, and finally, the electric water pump.

Through the decades, the elements of espresso brewing were tested and refined

to produce the standards we have today: one ounce of true espresso comes from exposing 1/4 ounce (7 grams) of finely ground and packed coffee to 195–205º F water under 130 lbs. (9 bars) of pressure. In a brief 25 seconds, most of the highly flavorful coffee aromas and oils are extracted, while the more bitter compounds and off-tastes are left behind.

When the ground coffee is fresh and the brewing is done well, the pressurized brew water emulsifies the coffee oils into the golden foam called crema, which crowns the espresso shot with ultimate flavor and aroma.

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Overextraction and underextraction

Brewing great espresso takes an understanding of what actually winds up in the cup when coffee is exposed to water. Roughly 30%

of a roasted coffee bean is made of water soluble compounds. 20% of those compounds dissolve fairly easily, while the remaining 10% take a little more work – which is a good thing, because that less-soluble 10% is acidic, bitter, and generally unpleasant. The goal of all coffee making is to extract the easily dissolved oils and compounds while leaving the rest in the grounds.

If ground coffee steeps in water too long, all the soluble compounds will be extracted, which makes for a very bitter brew. This

is called overextraction. The opposite of overextraction is underextraction, which occurs when coffee is not exposed to the brew water long enough, leaving the essential flavors and aromas locked in the grounds. Underextraction results in coffee that is weak in taste.

Whether brewed coffee is overextracted, underextracted, or just right depends on several factors, including the ratio of coffee to brew water, the fineness of the grind, the brewing temperature, and the length of time the water is in contact with the coffee. All these factors are either directly or indirectly affected by the barista’s technique.

Before brewing: the elements of great espresso

Before the espresso machine is even plugged in, you’ll need several elements to produce great coffee.

Fresh Coffee Beans

Great coffee can only come from fresh coffee beans, properly roasted. Many baristas recommend buying beans roasted no darker than a medium roast, the color of which appears as an even chocolate brown. This roast preserves the natural sugars and flavor of the bean, which sets the stage for excellent espresso. A medium roast is the darkest a bean can be roasted without oils developing on the surface.

Darkly roasted beans – which appear dark

brown or nearly black – look great, but the extra roasting overwhelms the more delicate coffee flavors and caramelizes any sugars. A heavy “roasted” coffee flavor, often bitter and sharp, will predominate with a dark roast.

To preserve the freshness of coffee beans:

Keep beans in an opaque, air-tight container and store them in a cool, dry place. Refrigeration is not recommended, as condensation tends to form on the beans whenever the container is opened. Freezing can help preserve beans stored for an extended period, but it will also impair flavor.

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