To dominico's point as to whether most home baristas would taste a difference of 2°F starting temperature, I think they would, with a dialed in shot (dose, grind) of a complex coffee. And yes, I'm referring to starting temperature. Some of this is coffee dependent.

drgary wrote:To dominico's point as to whether most home baristas would taste a difference of 2°F starting temperature, I think they would, with a dialed in shot (dose, grind) of a complex coffee. And yes, I'm referring to starting temperature. Some of this is coffee dependent.

Definitely coffee dependent. I suspect that darker roasts are much more sensitive to temperature differences because they extract more easily. Very light roasts, which are often hard to extract, may not respond at all to a temperature swing of 2F or even more.

Now, for roasts in the middle, I'm not so sure that "most" home baristas would be able to detect a temperature difference of 2F. Sounds like my pallette is not as sensitive to temperature changes as yours. But as with many claims about subtle flavor differences, I'd like to see some blind tasting data across a broad population of home baristas before agreeing.

Agreed that it's hard to generalize. BTW to an earlier note of yours, I pull some dark roasts with a starting temperature as low as 175°F and am able to eliminate harsh roasty notes and emphasize chocolate and nutty flavors. Again, it's coffee-dependent. What am I trying to bring out in that coffee? What do I not want to extract? 175°F is a temperature Alan Adler prefers in an AeroPress, and Alan likes coffees that are roasted into the start of second crack, i.e., dark roasts.

I haven't had very many shots, compared to many thousands many of you have enjoyed, but I've had enough while tweaking with my cheap little single boiler machine with a thermocouple on the boiler to know both profile and starting temp can cause very different tastes within a small range.

I've tried shots running the heater during the shot, which seems to make it bitter and flat.
I've bumped the heater a few seconds before the shot, which caused such inconsistent temps I can't remember the exact effect.
I've just now modded my machine to where I can start really testing by isolating the brew switch from the brew thermostat, so I can have more intra-shot control.

I pulled the first declining temp shot I've had in a month last night. Mind you, the boiler temp went from 200F to 190F in the 30 seconds. During the last month of pulling shots, the heater would be on the whole shot, and the boring, burnt shot taste was getting old. The start temp would be 199 and it would slowly come up to 203-204 at shot end. Who knows what the brew temp was. This time was much improved, with the fruit taste coming back, the burnt taste gone, more complexity.

I've read some of those reviews, and I notice that some people change the starting temp a couple of degrees to see what happens, and report changes.

dominico wrote:To the OP: I don't think having a specific stable temperature throughout the shot is all that important, in fact it could be detrimental depending on the coffee, since it could lead toward over extraction toward the end of the shot. There are definitely those in the camp that says a declining temperature profile is better.

^ ^
This.

Charlene wrote:Hi Redbone,

I suspect most people will go one way or the other depending on what machine they own or wish to own. It's human nature.

A serious study would need to take place to quantify blind tasting votes on a repeatable flat temp profile vs repeatable changing-temp profile in a taste off with two different machines going head to head.

I took it on expert advice that an HX machine makes nice tasting humpy temp-value related flavors in the cup.
I certainly can not say that that is not so.

Early days of enjoying espresso crafted for discriminating espresso lovers was in Catania Sicily and Milano in the '90s so that is my benchmark. Many lever machines were in use at that time. Guess you could say I imprinted on those Italian lever machines.

Not sure if you've followed the Decent Espresso machine development, but one of the key features touted is temp profiling , and the ability to measure the temperature in the basket and adjust temp during brewing. The main application / benefit claimed is that there is a cooling effect at the beginning of the shot and therefore the machine can bump up the water temp briefly at the beginning of the shot. And supposedly this results ain't superior tasting shots.

So in other words, a "humped" temperature profile, which sounds quite like what an HX machine does.

Why, yes I have been reading about their developments. Quite interesting work so far.

Btw, just brewed another espresso, a 1:1 ristretto using Redbird Espresso beans, with one of my three new VST filter baskets, the 18g one. Aside from the VST basket needing for me to adjust the grind a little finer than before, it seems to impart some temp flavoring itself in that it offers less impedance to liquid. I have to change my temp tables to allow for it. Nice cup though!

Peppersass wrote:Definitely coffee dependent. I suspect that darker roasts are much more sensitive to temperature differences because they extract more easily. Very light roasts, which are often hard to extract, may not respond at all to a temperature swing of 2F or even more.

Now, for roasts in the middle, I'm not so sure that "most" home baristas would be able to detect a temperature difference of 2F. Sounds like my pallette is not as sensitive to temperature changes as yours. But as with many claims about subtle flavor differences, I'd like to see some blind tasting data across a broad population of home baristas before agreeing.

My very short experience has been the opposite.
Light, bright roasts have varied a lot with small temp variations. Most of the blends I have tried have been bright, fruity types.
I found Caffe D'arte's decaf espresso to have the same, kinda bland burnt taste all the way from 202*F to 195*F start temp. The only way I got the taste to sweeten and the burnt ash part to go away was pulling starting at at 195F* and declining. Not much complexity still.

I'm finding by blipping the steam switch prior to starting a pull, I can somewhat mimick that humped profile of HX machines because of the boiler's inertia. I'm going to experiment with different beans using this method to compare to a straight, declining temp profile.

drgary wrote:"dominico wrote:
To the OP: I don't think having a specific stable temperature throughout the shot is all that important, in fact it could be detrimental depending on the coffee, since it could lead toward over extraction toward the end of the shot. There are definitely those in the camp that says a declining temperature profile is better."
^^^
This.

I'm going to bring in a link to your 2016 taste test: Favorite Espressos 2016

I note the temp drop you mentioned on the Prestina seems really similar to my tiny single boiler, about 15*F average drop by 30 seconds at end of shot pull.

All of my attempts at tweaking various temp profiles, (using my trusty steam heat switch) whether humped, flat, rising, falling, etc, using the falling temp profile has revealed the broadest spectrum of flavors tasted in a given shot, if that makes sense. While I don't have a declining pressure, due to a pump, I think my results may be very similar because of temp profile. Personally, I have found it to be the best IMO.

Maybe small boilers aren't so bad after all?