Water is often referred to as the universal solvent in relation to coffee brewing. The higher the water temperature, the more solvency it will have. This will determine how rapidly we can break down and extract all of the various organic compounds in a given coffee. Molecules move faster and faster as the temperature rises and thus, are capable of extracting those delicious flavors from your chosen coffee. This being said, hotter water is not always best. What we want is water in the ideal temperature range for the level of roast of the coffee we are brewing.
So you may be wondering…how do I know what water temperature to use? The Specialty Coffee Association recommends 195°F-205°F as the ideal brewing temperature range. While this is sufficient for most coffees, any coffee that is roasted darker (think Verve's Buena Vista blend) would most likely taste sweeter at 180°F-190°F. Some people might tell you that a darker roasted coffee is more soluble, and that seems logical, but in reality, a lighter roasted coffee is more soluble! The darker a coffee is roasted, the most compounds have been roasted away and although the cell structure is more broken down, there are less solubles available. Using a water temperature that is too high (most likely anything over 195°F), the potential for over-extraction and bitterness increases dramatically. As well, the reverse is true for medium and lighter roasted coffees. If the coffee you are using is a light roast, using a higher temperature somewhere in the range of 206°F-208°F will help to penetrate the dense cell structure and extract all of those delicious sugars so that your resulting brew doesn't have an acid heavy flavor to it. Regardless of the coffee being used, the ideal brew should have a balance and display whatever flavors are in the whole bean.
The Stagg [X] and [XF] Drippers have double-walled vacuum insulation which helps to maintain that water temperature in the coffee bed. That insulation promotes an even temperature level throughout the coffee bed which is a key to proper extraction, and thus, a balanced brew. The Stagg EKG has to-the-degree temperature control which allows that very specific water temperature you have decided to use for the natural processed Catuai from Costa Rica. Using the two in unison will give you a very stable temperature throughout the entire brewing process. It also allows the opportunity to see the effect one or two degrees in temperature hotter or cooler can have on a specific roasted coffee. I recommend always starting with the same water temperature if the roast level is similar, and then adjusting higher or lower from there depending on whether you want more or less extraction.
We all have different taste preferences. Knowing what type of roast you prefer and the resulting flavors that degree of roast tends to offer will make it that much easier to have the best cup of coffee in the world. The best cup of coffee in the world being the one that you truly enjoy, and don’t worry, there can be many of them!