We’ve just started stocking a range of thermal cafetieres and it got me wondering what’s the actual point of them? Yes, I know they keep your coffee hot for longer. This new cafetiere claims to keep it hot for 3 times as long. But if you leave your coffee in the cafetiere doesn’t it keep extracting?

This is something I’ve read and heard many times but never got around to testing for myself. Does coffee really keep extracting even when the plunger is down? So I conducted a test using a TDS meter, measuring some coffee immediately after I’d finished brewing and then again 5 minutes later. The results showed that the coffee which had been left in the cafetiere was indeed stronger, by 6%.

This might not seem a lot, but the aim of brewing is to extract all the desirable flavours from the coffee whilst leaving the undesirable ones behind. So if all the desirable flavours have already been extracted by the time the brew has finished, than this extra 6% of strength will be from the undesirable flavours.

Therefore, keeping your coffee hot for longer isn’t a good selling point for a cafetiere. If you leave your coffee inside it, it’s going to keep on brewing, and when you come back to it, it will taste darker, bitterer and will contain more caffeine.

Temperature Stability

So what use is a thermal cafetiere if you can’t store coffee in it? Well, one idea that I came up with is that it should keep a more stable temperature compared to a conventional glass cafetiere and so should be more efficient at brewing. Back to my testing lab (I don’t actually have a lab); I brewed a thermal and a conventional cafetiere and measured the strength of their coffee. After only 3m 30s the thermal one was a staggering 25% stronger. The temperature of the water in the thermal cafetiere had only dropped 3.7°C during the brew, whereas the glass one dropped 7.9°C.

Admittedly, conducting this test only once isn’t very scientific, especially when there are many other variables affecting extraction. But 25% is a significant difference, so even if I were to redo this test, I’m pretty certain the thermal cafetiere would prove again to be the more efficient brewer.

So there you go: thermal cafetieres are quicker at brewing coffee, just remember to pour your coffee into something else after you’ve finished brewing.

Tags: cafetiere, coffee maker

This entry was posted on Friday, May 21st, 2010 at 8:46 pm and is filed under New Products. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.