Most every kitchen in the western world has a coffee pot or brewer of some sort gracing the counter top. The most common item, without question, is the plastic shelled drip coffee brewer.
The majority of these tend to have a burner or warming element built in. The thing that is critical here, with the drip brewer, and an important consideration in finding the right espresso machine, is the ability of the machine or brewer to heat water to the correct temperature.
Now I am not going to get into the classic argument of what is or what is not the ideal temperature, but let us agree, for a moment, that it is 195-200 degrees Fahrenheit.
You may be surprised to find that the hot coffee that you have been drinking lately is not really that hot at all. Not that this should bother you much, but you may be encouraged to achieve a better brew temperature if you realize that the rate of extraction and resulting quality of brew is temperature dependant.
This rule also applies in espresso, but more on that issue later.
The average brew basket temperature in most consumer coffee brewers is probably less than 175 degrees Fahrenheit. Good news is, industry has tuned into the benefits of hot coffee and ideal extraction times and temperatures. Yes, folks, extraction time is critical in drip brewers and it is super-critical in espresso preparation.
What have we established so far? We know that temperature is critical in achieving a successful brew interval in virtually any style of brew method. With espresso, and espresso-based beverages, like the cappuccino, the beverage is consumed right away or prepared, if you would, for immediate consumption. There is no consideration for warming, re-heating or otherwise storing the beverage for later consumption, so donít even think about it!
Gravity and pressure: At least one of these two factors is present in all styles of coffee preparation. Whether a cup or pot of coffee is being prepared with a drip pot, a press pot, a filter flask, thermal carafe or an air-pot, the common physical property is gravity and normal atmospheric pressure, nothing more. The process of brewing espresso requires a critical brewing temperature, a specific rate of extraction or brewing period and pressure, lots of pressure.
In the world of espresso brewing, the term bar or bar pressure is a measure of machine performance and capability. Simply, one bar equals one atmosphere or unit of air pressure at sea level. Pump driven espresso machines deliver anywhere from 9 to 20 bar, depending on the type of pump and its configuration within the brew group.
It is important that we do not get hung up on pump pressure because virtually all machines have the same pump, at least most of the home consumer and semi-professional models anyway.On to chapter three!
