BTW, could not one of those electric kettles that keep water at a certain temperature for a period of time work as a poor man's sous vide?

I spent a bunch of time playing with this today, as I spent nearly the whole day at home grading papers. I found that the microwave technique works just as well as the sous vide and water bath, which is a great relief. I got fantastic shots of several brew roasted coffees this way, including the Gedeo Kochere, the Don Pachi, and some excellent Kenya Gatomboya AA from Mountain Air. I feel worried that maybe I'm falling for a fad, but the microwave method is so easy, and the results so nice, that I'll probably stick with this is as my standard approach to pulling light roasts for a while.

IMAWriter wrote:So, the heat generated can be deleterious, but the beans themselves pre-heated isn't?

The amount and time of heat is not enough to cause chemical change. At least that's the hope. I suspect part of the effect might just be having the coffee come to temperature more rapidly rather than anything more dramatic.

IMAWriter wrote:BTW, could not one of those electric kettles that keep water at a certain temperature for a period of time work as a poor man's sous vide?

Yup, that's perfect. You could use the Bonavita. And I use Ziplocs for sous vide. No fancy vacuum sealer is required.

NoStream wrote:Yup, that's perfect. You could use the Bonavita. And I use Ziplocs for sous vide. No fancy vacuum sealer is required.

I think I meant to say heat from a GRINDER can be harmful, but this technique not so?
Can't believe doing this in a "nuker" to Don Pachi. Oh, the humanity!!

I think the main goal is to keep the beans from staying hot long enough for volatility to reduce their punch and aromatics.

I tried this last weekend using my bonavita as a warm water bath. However, the bonavita will only go down to 140F, so I cut the power around 105F to coast up to ~115F where it held fairly steady for 20 minutes. And using a Pharos, my typical 50% brew ratio shot time (16g in, 32g out) decreased from 30s to 18s. The resultant brew was drinkable and the wife commented that it seemed "smoother". I have to believe the dominant effect here is that we're effectively altering the grind size distribution, and reducing fines due to more pliable beans. At these low temps, I wouldn't think we're affecting additional changes to the bean chemistry beyond what was achieved during roasting. Thoughts?

[creative nickname] wrote:I found that the microwave technique works just as well as the sous vide and water bath, which is a great relief.

What parameters did you use (weight of beans, microwave setting, time). What's your microwave power rating?

IMAWriter wrote:Can't believe doing this in a "nuker" to Don Pachi. Oh, the humanity!!

Keep in mind, I didn't try this with the fancy stuff until I had first tested it on cheaper coffee, and found that it improved over the shots I was getting otherwise! And for what it is worth, microwave heating gets a bad rap. You have to understand some of its peculiarities -- in particular, that it heats water molecules preferentially and can have difficulty penetrating to the center of a large mass of moist food -- but when used in the right ways you can get very good results.

Roasted coffee is very dry, so that means that there isn't much water in the beans to heat. Ergo, the microwave heats the beans very gently. Moreover, since there is only a small, concentrated mass of beans to be heated, dead spots don't seem to be much of a problem, and the beans seem to heat quite evenly.

Peppersass wrote:What parameters did you use (weight of beans, microwave setting, time). What's your microwave power rating?

My microwave is an 1100W Frigidaire. I used full power, varying the time to take account of the mass of beans I was heating. A 9.5g dose for a single shot of espresso would get about 20s, while a 20g dose for a pour-over would get 45s or so. I check the beans using my fingers at the end, feeling to ensure that they are evenly warm but not hot. So far this has worked very well, and I haven't noticed any flavor differences from the sous vide approach.

This all seems interesting, but Tom, why haven't you repeated your initial experiment of 170F for 2-3 minutes? That seemed to make the most day/night, unmistakeable difference in your tasting, but everyone seems to be working at the 115F for 40 minutes with differing results.

Also, i presume the beans have t be warm when ground? One test to see if there is a permanent chemical change or something in the bean fracturing is to warm them, then let them cool and see if the difference remain or if the coffee goes back to baseline (or worse).

I might have to give this a try with some Compass delirium, but i'm going to go for the 170F for 2-3 minutes.