dustin360 wrote:I try and test common wisdom's held in coffee. Mostly cause Im a nerd, and what to know why. But also cause Ive told people a million times to "brew at this temp, fines are bad, brew for this long, dont pre grind, etc". And when they ask why, id much rather have experience that im drawing from.

It makes me wonder if a declining temp profile during brewing might be better for some coffees that have alot of florals. Maybe my next experiment will involve lowering the temp (mid brew) by 20 degrees or so...

Power to you. I think its essential that we all strive to do the same.

As for declining temp slopes as brew elapses, I have a sneaking suspicion that this indeed results in better coffee than flatline brewing. I have not tested this vigorously by any means and is simply based on the following observations: Most brews, including (and especially) the "standardized way" of tasting coffee, have a declining temperature as the brew elapses. Most of the methods that do so consistently result in tasty coffee for me.

One of the few methods, in brewed coffee, that can maintain a tighter range of temps (coming closer to flatline) is syphon/vacuum brewing, because of the addition of heat throughout the brew. I think of all methods, syphon/vacuum brewing is the hardest to get right...why? All over the place you'll see people talking about popcorn taste/smell, or cloth taste (we often blame the filters, but I think they are rarely the culprits), or bagginess in vacuum brews. I think this has to do with temperature. Again just an opinion based on my observations. I have had amazing coffee from vacuum brewers, but unlike most other brewers, a recipe that results in a good extraction is not easily translated to other coffees.

To me it makes sense that as we approach the higher percentages (18%-22%) of extraction yield towards the end of a brew, temperature decrease is a benefit. As we lose heat or energy, extracting the nasty things that would end up in our cup becomes harder, making our jobs easier, and our results tastier. just a theory.

I am excited to continue learning about both vacuum brewing and the effects of temperature decline on brewing.

As for your experiments: if you can get your hands on one, a dual-input Fluke with two bead thermocouples works magic in telling you what is happening in your slurry. You can place one near the top and one near the bottom of your slurry and then see what happens as you brew! If you are using a substantial amount of water in your kettle I don't think your brew will drop 20F, so if that is your intention, you may need to use a second kettle with cooler water. Post your results!