Espresso 101

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Espresso is a delicious and subtle beverage, both sweet and a little bitter at the same time.  It should have a rich syrupy mouthfeel, and a head of cinnamon colored crema.

Espresso is made by forcing 1--1.5 ounces of water at between 195 F and 205 F through 7 -8 grams of coffee, ground finely and tamped so as to take 25--30 seconds for the pour. There is a balance between the fineness of the grind and the force of the tamp that creates the resistance necessary for the timing to be exact. This allows the sweetness of the coffee to be extracted while leaving the bitter elements behind.

Grinding is important for any method of brewing coffee, but especially for brewing espresso. Imagine a little chunk of coffee bean soaking in hot water. First the good things soak out of the coffee chunk, the  bad things start soaking out. The trick is to get the good stuff and leave the bad stuff behind. Now imagine if there are big chunks and little chunks together in the hot water. By the time the good stuff has soaked out of the big chunks, the good and bad stuff has soaked out of the little chunks. A good grinder will produce very evenly sized and shaped pieces of coffee that will extract evenly. Burr grinders do this much better than the small grinders with the little blade that spins. Burr grinders typically have a container on top of the burrs to hold the whole beans and a container below to catch the grounds.

Espresso grinders are specialized. Espresso requires a grinder which grinds evenly and finely, with a lot of control of the fineness.  Believe it or not, the number of 'clicks' or settings on a espresso grinder is important. If your espresso is pouring too fast, you adjust the grind a little finer. If it's pouring too slow, you adjust your grinder a bit courser. The more fine your control of the grain, the easier it is to zero in the perfect shot of espresso.

There are many espresso machines and grinders on the market. There are six basic types of machines to choose from: steam powered machines, single boiler machines, heat exchanger machines, double boiler machines, and superautomatic machines, which come in a variety of boiler configurations.

Steam machines are the ones you see inexpensively offered at department stores. They are characterised by a screw-on lid to a water chamber that holds just enough water for one carafe of espresso. By heating the water, steam pressure alone forces the water through the coffee grounds. These reach a maximum pressure of about 3 bars, as opposed to the 9 bars of a pump driven machine. Many refer to the coffee made from these machines as 'mokka' rather than espresso. It's not the ideal espresso machine, but they can make good drinks nonetheless.

The entry level pump machines, which can force the water through the beans at 9 bar, or 9 atmospheres of pressure,  use a thermoblock to heat the water for espresso and steam. These machines are better than steam machines, but unfortunately the thermoblocks rarely provide stable temperatures, and this can effect the flavor of the espresso.

Once you move up to a boiler machine,  the machines are usually single boiler machines. These have one boiler for both brewing espresso and for steaming the milk. After making the espresso, which is brewed at around 100 C, you then activate a switch which heats the water up to about 150 C, for steaming milk. This is usually not a problem when brewing occasional milk drinks, but if you make a lot of milk drinks you may not want to wait for the water to heat every time. These types of machines are able to make drinks often as good as commercial machines,  and if used properly and with fresh, good beans they can make better drinks than most coffee shops sell!

If you make lots of cappuccinos and lattes and like to entertain, you can move up to a heat exchanger machine, the same design as most commercial machines. For home machines, these start at around $1000, so they are for serious users. They  have a boiler always heated to steaming temperatures. The water for brewing passes through a heat exchanger inside of the boiler to heat the water for the espresso. This allows you to steam without waiting, even at the same time that you are brewing. Heat exchanger machines usually deliver fairly stable temperatures, but if you want REALLY stable temps to  produce the most perfect espressos, you can move up to a double boiler machine. There are only a few of these manufactured, with the La Marzocco considered the finest commercial machine manufactured. However, Reneka, a French company, is now producing a small machine suitable for home or light commercial use, with double boilers and some very high-tech features. Only the most serious coffee geeks go the expense and effort of importing these machines.

There  are a whole new generation of espresso machines becoming popular, the superautomatics. These machines grind, tamp, brew, and often steam milk with the push of a single button. These are available for home use, starting at around $500, with the commercial versions going for upwards of $5000. They really don't make as good an espresso as the traditional machines, but they sure are easy to use.