Whole bean coffee that you grind yourself is preferable to pre-ground, too. The bean’s exterior traps and protects all of the delicate, volatile, and water-soluble oils that give coffee its flavor. As soon as you break the protective shell, it’s easy for the flavor to get contaminated, and much of the aroma escapes as soon as the oils are exposed to air.
The principle of a vacuum brewer was to heat water in a lower vessel until expansion forced the contents through a narrow tube into an upper vessel containing ground coffee. When the lower vessel was empty and sufficient brewing time had elapsed, the heat was removed and the resulting vacuum would draw the brewed coffee back through a strainer into the lower chamber, from which it could be decanted. The Bauhaus interpretation of this device can be seen in Gerhard Marcks' Sintrax coffee maker of 1925.
Why it's great: A true espresso drinker knows that when it comes to espresso, there are a few things that can't be overlooked when it comes to a quality cup: freshness and a good grinding method. The burr grinder is a known Barista-favorite, as it maximizes the surface area of the grinds resulting in optimal flavor. The BES870 even allows you to adjust the grind and portion size, so you can go from fine to course depending on your desired flavor. 
For hundreds of years, making a cup of coffee was a simple process. Roasted and ground coffee beans were placed in a pot or pan, to which hot water was added, followed by attachment of a lid to commence the infusion process. Pots were designed specifically for brewing coffee, all with the purpose of trying to trap the coffee grounds before the coffee is poured. Typical designs feature a pot with a flat expanded bottom to catch sinking grounds and a sharp pour spout that traps the floating grinds. Other designs feature a wide bulge in the middle of the pot to catch grounds when coffee is poured.
The very first espresso machines worked on a steam-pressure basis, and they’re still in use today. With this type of machine, steam or steam pressure is used to force water through the coffee grounds and produce espresso. Some steam-driven machines can produce a measure of foam “crema.” But they can’t generate enough pressure or provide the precise temperature control necessary to produce true espresso: They simply make a very strong cup of coffee. However, they cost considerably less than pump-driven machines. Our verdict is that if you’re a true espresso lover and seeking to make a good shot at home, we recommend you steer clear of steam-driven machines. They’ll likely disappoint you.
It can take a little while to get to know the ins and outs of a new coffee maker. In CR’s labs, each drip coffee maker we test brews roughly 65 cups by the time our engineers are through with it. And brewing is just one of many aspects we look at. We test for handling and convenience, too, so you can choose a model that helps you sail through morning madness. 
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