The Physics Factbook
Edited by Glenn Elert -- Written by his students
An educational, Fair Use website
topic index | author index | special index
|Ramsey, William L. Physical Science. Holt, Rinehary & Winston Publishers. 1986: pg 121.||"When the coffee maker is started, the water is heated to 100 °C."||100 °C|
|McGee, Harold. On Food and Cooking. New York: Scribners, 1984: 222.||"This takes about two minutes of contact with water at about 200 °F (93 °C)."||93 °C|
|Brewing Great Coffee. virtualcoffee.com. April 2000.||"The coffee brewer should produce a brew water temperature of 200 degrees F (+or- 5 degrees)."||91 to 96 °C|
|Navy Coffee! Koffee Korner.||"Urn Bag Method, 1945 Cook Book of the United States Navy, Page 35 … Fill jacket of coffee urn with water 3/4 full as indicated on the gauge glass. Maintain temperature of this water at 185 °F to 190 °F."||85 to 88 °C|
|Frequently Asked Questions. Coffee Classics. 2001.||""Brew temperature is very important and yet a matter of personal preference. We suggest you try for a temperature of about 190 degrees, not over 200 degrees for the water temperature as it touches the grounds."||88 to 93 °C|
Everyone likes to drink a fresh cup coffee in the morning, but does one possess the expertise of making freshly brewed coffee. Brewing coffee is a method in which water is being flavored with roasted, ground coffee beans. The different types of brewing methods are filter cones, electric drip machines, plunger pots, and percolators.
One third of a liter for every 17 grams is the standard measurement for making good coffee. If coffee is brewed for too long it will taste bitter. The best level of extraction of coffee is 20% of the solids in the grind. This is achieved by keeping the brew water temperature between 88°C and 93°C. If the temperature of the water is too low, underextraction will occur and the coffee will be too weak. Underextraction will cause the coffee to have a sour flavor, since the acids from the beans are the first substances to dissolve. If the brew water temperature is too high then over extraction will occur and the coffee will taste bitter. Increasing the amount of coffee used can decrease over extraction of coffee. The entire brewing process should about four to six minutes. If the brewing process takes less than four minutes, the ground particles have to be smaller and more powdery. If the brewing process takes longer than six minutes, than the ground particles have to larger.
Brewed coffee is about 98% water, so it is important to have good quality water. Filtering tools are used in order to filter out chemicals that may cause the coffee to taste bad. If softened water is used for brewing coffee it will slow down the extraction and dilution process, which will result in the over extraction of coffee. The flavor of coffee will deteriorate if it is held in an open container for longer than 20 or 30 minutes. Fresh coffee is best because once the coffee gets warmer the organic materials of the coffee will start to break down and the coffee will develop a bitter taste. If you need to keep brewed coffee warm for a longer period of time use a thermal container that will keep the coffee warm without heating. Coffee can be held in a container for up to 45 minutes before the flavor will start to deteriorate.
Diana Gendler -- 2003
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