common sense of coffee 2

Temperature

For coffee brewing, the Specialty Coffee Association of America (SCAA) prescribes a water temperature of 92 - 96 degrees C (195 - 205 degrees F); see The Basics of Brewing Coffee by SCAA Executive Director Ted Lingle. Avoid boiling then cooling the water to the proper range, or at least letting it boil for more than a few moments; boiling hot water rapidly loses dissolved air and will taste flat. If the water is too cool, the brew will be sour and underextracted. The temperature range during brewing should not vary by more then a few degrees, or extraction will not be optimal. Temperature loss often occurs as a result of heat absorption by the equipment itself (for example, if an espresso machine's portafilter is not kept warm between shots by storage in the machine) or into the atmosphere (as in a uninsulated glass French press during the approximately four minute steeping period). Pre-warming the equipment or insulating it, respectively, will solve these problems.

Water quality

Coffee is 98.5 to 99 percent water, so water quality will critically affect the resultant brew's taste. When making coffee, you should only use water that tastes good enough to drink straight. As a result, the best cups of coffee are made with filtered tap water or bottled water. Carafes or sink-based filters will likely perform better and have a lower per-gallon cost than the modest charcoal filters that some manufacturers include with their auto-drip machines. Do not mistake distilled water for filtered: the former is missing minerals that contribute to the water's taste and aid in extraction. When certifying a coffee brewer, the SCAA uses fresh cold water containing a formulation of between 50 to 100 parts per million dissolved minerals. The water should be fresh; it it has been sitting too long (or has been heated then cooled), it will be missing the dissolved air that is an important component of the water's taste.The water should also start cold: hot water has lost some of its dissolved air, and may have picked up minerals or solubles from your pipes.

                                                                 ShengWu