The trend in both commercial and home coffee brewing in the past 10 years is definitely moving from brewing into glass pot toward brewing into a thermal dispenser such as an airpot or a thermal carafe.
Why Switch to an Airpot?
The advantages of airpots and thermal carafes:
- The coffee does not sit on a warmer and burn. Coffee in a glass pot must sit on a heat source. Coffee is best when is it is not subjected to heat for a long time – the heat affects the flavor compounds and breaks them down, which results in bitter, burnt-tasting coffee.
- Since there is not a heat source, nobody is going to leave a warmer on overnight or over the weekend. It’s a bad start to a morning when one of the first tasks of the day is cleaning up a burned pot of coffee.
- With an airpot or thermal carafe, the coffee doesn’t have to stay near the brewer. Think about it – if a heat source isn’t necessary, the airpot or carafe can be carried anywhere and set on a table – without harming the table.
To conduct the experiment, we started by simply boiling water and pouring it into our airpot. For our airpot, we used a Zojirushi Air Pot model AASB-22B, which is 2.2 Liter, glass-lined, and lever-action operated.
Zojirushi is a Japanese company, but their airpots are made in China, as are every airpot of which we are aware. That said, the quality of airpots can vary significantly, and the price is a pretty good gauge of the quality.
Zojirushi states their heat retention rate as 169°F @ 10 hrs. and 145°F @ 24 hours – assuming a starting temperature of 203°F.
Airpot Temperature Readings:
The boiled water was 203°F upon entering the airpot. We did not heat the airpot before pouring the hot water into it – since most people don’t do that. Therefore, there was an immediate loss of 9 degrees. Temperature measurements were taken every 15 minutes.
|Water Temperature Upon Pouring into Airpot||203°F|
|1 Hour and 15 minutes||187°F|
|1 Hour and 30 minutes||186°F|
|1 Hour and 45 minutes||185°F|
|2 Hours and 15 minutes||183°F|
|2 Hours and 30 minutes||183°F|
|2 Hours and 45 minutes||182°F|
|3 Hours and 15 minutes||180°F|
|3 Hours and 30 minutes||180°F|
|3 Hours and 45 minutes||179 °F|
|4 Hours||178 °F|
Obviously, the temperature loss is gradual, so the question becomes where to draw the line and say the coffee has gotten too cold.
Coffee should be brewed at 195-205°F. It immediately loses a few degrees of temperature after going through the grounds and exiting the filter basket and entering whatever container is used to hold it. Some people really love their coffee hot, which would mean about 180-190°F or so. For others, coffee can still taste pretty good at temperatures as low as 150°F – especially if the quality of coffee is good and the heat isn’t just masking the lack of flavor.
A good airpot can keep the coffee at an acceptable temperature for a good 3-4 hours – acceptable to most people, at least. Just make sure you buy a quality airpot.