jim_schulman Senior Member Joined: 19 Dec 2001 Posts: 3,772 Location: Chicago Expertise: I live coffee
Posted Mon Sep 6, 2004, 4:32pm Subject: Re: How to Minimize Sour Taste at Beginning of the Pull?
toms Said:
I haven't tried draining the first seconds of the shot but the idea makes sense. I've been doing a lot of experimentation with my (almost) three-month old Valentina. Someday I may even get a review written. I like the time/volume graph. Any way to access more info like that?
(it is very hard to keep a straight face while typing this...)
It might be more accurate to say not enough hump is not good, since it affects more than just the first third of the shot. This is sort of restating what you said in your last point ("Alternatively, you can flush a little less before the shot and hit the puck with very hot water."), however I've found that the flush amount affects the last two-thirds more than the first third, and if it's off, it's rarely for the better. In contrast, the wait time's effect is front-loaded and more ephemeral in all but the extreme cases.
One thing I like about the prosumer E61s is that their temperature profiles are somewhat "mallable." You can push-and-pull to produce different curves and they produce different shot characteristics. The commerical machines, like the Cimbali Junior and La Marzocco (below), produce a profile that is uniquely theirs and there's very little you can do as an operator to change its shape (a good thing in a commercial environment). This is one reason I would like to see the SCAA barista competitions go to more classical, less "advanced" designs -- to raise the level of difficulty. Otherwise someday we'll all be nodding off to the play-by-play banter of the SCAA Super-Automatic Challenge. ;-)
jim_schulman Senior Member Joined: 19 Dec 2001 Posts: 3,772 Location: Chicago Expertise: I live coffee
Posted Mon Sep 6, 2004, 6:11pm Subject: Re: How to Minimize Sour Taste at Beginning of the Pull?
HB Said:
It might be more accurate to say not enough hump is not good, since it affects more than just the first third of the shot. This is sort of restating what you said in your last point ("Alternatively, you can flush a little less before the shot and hit the puck with very hot water."), however I've found that the flush amount affects the last two-thirds more than the first third, and if it's off, it's rarely for the better. In contrast, the wait time's effect is front-loaded and more ephemeral in all but the extreme cases.
I really can't comment on the technique directly, since there's no way to experiment with this without a dattalogger. I can do side by side shots with waits after flushing. My first tries were different enough to make it worth while. The blend I'm using is fruit heavy, with subdued caramel roast tastes. The wait produced a shot where the roast taste was much more prominent and long lasting, a sort of mollases-toffee, really quite tasty.
Does the effect of a wait carry over into subsequent shots? If you advocate E61s for barista competitions, you'll need to characterize 2 and 4 shot sequences in any case.
Posted Mon Sep 6, 2004, 7:27pm Subject: Re: How to Minimize Sour Taste at Beginning of the Pull?
jim_schulman Said:
Does the effect of a wait carry over into subsequent shots? If you advocate E61s for barista competitions, you'll need to characterize 2 and 4 shot sequences in any case.
It's funny that you mentioned roast tastes, I've noticed the same thing. Allowing a larger hump seems to push forward the roast notes, especially for darker roasts. For light roasts, it tends to enhance the shot's complexity, or so it seems to me. Regrettably I don't have the vocabulary or roasting experience to explain it, however your description sounds right.
The carry over from shot-to-shot is a factor, but very little for the wait period we're discussing, and it depends again on the machine. I had the chance to try out the Cimbali Junior for a few weeks. As you see below, it has a very distinct temperature profile, which I must assume is intentional since it shows up consistently, independent of the flushing regime I employed (note: these are preliminary results and I welcome corrections from Junior owners).
Back to the E61s, I noted they do tend to "flatten out" if pushed shot-after-shot, but if you want to get a high-hump curve like the one below, it doesn't take long, especially if you're willing to crank up the pressurestat (say +1.2 bar). There's no technical reason an HX / E61 couldn't be the standard for competition, and I expect it would reveal a larger point spread between the top 10 competitors. The bad news is that the judges would likely be subjected to more iffy shots.
jim_schulman Senior Member Joined: 19 Dec 2001 Posts: 3,772 Location: Chicago Expertise: I live coffee
Posted Mon Sep 6, 2004, 8:49pm Subject: Re: How to Minimize Sour Taste at Beginning of the Pull?
I'm trying to figure the mechanics behind the humps. Here's my guess:
On the 1.2 liter E61s, the HX itself is tiny, holding 20 to 30 mL of water. The long flush is needed to get all the E61 metal and the rest of the water in the entire thermosyphon loop cool. The pause allows this 30mL to heat up a bit, but it's effect is concentrated on the start of the shot.
On the Juniors, I'm guessing the initial water comes solely from that stored in the HX, while the later portion comes from a mix of incoming and stored water.
Your readings explain something that's been bugging me. All three machines (E61, Junior, and LM) are very temperature stable, and I've compared shots run at roughly the same temperatures (203-205). But to me, the Cimbali and E61 shots were always very similar, whereas the LM shots always seemed different, with subdued roast tastes and amplified origins (so much so that my home blends usually don't work on LMs). Perhaps, it's the hump profile the Cimbalis and E61 share versus the flat LM one.
BTW, I hear you're testing the Andreja. I'll be interested to find out if the the 1.8 liter boiler and larger HX may make it very different from the 1.2 liter machines.
Posted Tue Sep 7, 2004, 4:43am Subject: Re: How to Minimize Sour Taste at Beginning of the Pull?
jim_schulman Said:
BTW, I hear you're testing the Andreja. I'll be interested to find out if the the 1.8 liter boiler and larger HX may make it very different from the 1.2 liter machines.
Actually, their HXs are the exact same volume (110ml, according to Chris Cramer, one of the techs at Chris' Coffee). Judging by the schematics and photos, I would guess that Junior's HX is 3-4x larger. It's obvious when you use the machine that the HX is huge -- I pulled a 60 second test shot and the temperature did not vary more than a degree for the last 40 seconds (it stopped measuring because of the pump auto-shutoff at one minute). The prosumer E61 machines are clearly tuned to single-shot performance, since their temperatures invariably plunge around the 30 second mark.
I haven't done systematic measurements, but it appears the water in the HX reaches boiling point very quickly -- on the order of 45 seconds to one minute. Its temperature is dampened by the rest of the brew group pathway, but only up to a point. I think the size and speed of "hump onset" correlates to the volume of the HX water that's beneath the boiler water level. At least that makes sense to me because steam doesn't conduct heat nearly as well as water.
Ah well, it's interesting how these little beasts work, although I suppose it's minutia from a typical user's viewpoint... :-)
Posted Tue Sep 7, 2004, 5:38am Subject: Re: How to Minimize Sour Taste at Beginning of the Pull?
Great thread folks! Especially for me, a very recent convert to an E-61 HX machine (QM Andreja), trying to break PID'd Silvia habits and full of questions, many of which have been answered by Dan and Jim. Nothing has caused me to appreciate the PID on my now sold Silvia more than this transition. I feel like I'm working blind in an area where I was previously so well informed (temperatures) and have gone backwards to the initial temp-surfing, pre-PID days of my Silvia. I hope that by developing new habits (flush timing, amount of flush water, etc.), I can regain some sense of control and sanity! Right now I feel as though I've jumped off a cliff!
Posted Tue Sep 7, 2004, 5:51am Subject: Re: How to Minimize Sour Taste at Beginning of the Pull?
boby Said:
I hope that by developing new habits (flush timing, amount of flush water, etc.), I can regain some sense of control and sanity! Right now I feel as though I've jumped off a cliff!
I hasten to add that we're really splitting hairs in this discussion. If you observe the "water dance" closely during the cooling flush, it is not difficult to get consistent temperatures shot-after-shot. Observation is ultimately a more reliable measurement than volume or time. I PID'd a single-boiler Amica and agree it is very convenient, but IMHO, it doesn't require that much skill and practice to produce the same reliable results from an equivalent HX.
Posted Tue Sep 7, 2004, 9:16am Subject: Re: How to Minimize Sour Taste at Beginning of the Pull?
Guys, The research, data, and experiences you're sharing here on coffeegeek are amazing. Newbies like myself benefit greatly from your time, effort, and knowledge.
HB Said:
If you observe the "water dance" closely during the cooling flush, it is not difficult to get consistent temperatures shot-after-shot. Observation is ultimately a more reliable measurement than volume or time.
Posted Tue Sep 7, 2004, 1:31pm Subject: Re: How to Minimize Sour Taste at Beginning of the Pull?
Wow. Thank you so, so much. I don't yet have a temperature probe, yet am almost certain my water is way too hot, due to the amount of dancing I see in my cooling flush. I'll try a much longer cooling flush, looking for the water to settle down to a nice, steady stream for a few seconds at least before extracting the first shot.
This video is a must-see, I believe, for anyone with a prosumer HX / E61. If I hadn't have seen this video or probed the portafilter myself, I never would have known the grouphead was getting so hot.
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