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Systematically Improving Espresso: Insights from Mathematical Modeling and Experiment

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  • #61
    Hi Luca,

    With the dark roast Brazil using the same grind setting and 20g dose in IMS B702TH26.5M (16 - 20g) will produce 40g in 30 - 32sec.
    At the same grind setting usually i would cut this short at 20 - 25g out in shorter time. Otherwise its unbearabley bitter and roasty, which i find people who request strong milk coffee like anyway. Even so, I would usually pull these at 89 or 90C to temper the bitter roast flavours and do not particularly find it that palatable straight up.
    I tested the last 3 quick shots at 90, 93, 95 and preferred the 95, it tasted sweeter and bolder, maybe a touch bitter aftertaste than 93.

    The 15.5g dose / quick shot ends up slightly less chewy but there's still plenty of silky coating mouthfeel with very little harsh flavours.

    So many of the ordinary cafes (around my area anyway) using run of the mill commercial/commodity dark blends could really benefit from this approach.

    Comment


    • #62
      James Hoffman has just posted his take on the research in his latest Youtube "Weird Coffee Science" video.

      https://m.youtube.com/watch?v=BoYBLn9hRqs

      A very interesting concept which could have wide ramifications on the economics of running a cafe.

      Comment


      • #63
        Sprometheus has put up a vid on it too:

        https://youtu.be/dVIzADFFZKs

        He tests it out in a shot comparison too, but I don't think he lowers the brew pressure, sorry only had time to skim will watch later

        Comment


        • #64
          Originally posted by luca View Post
          What are you shooting for in this shot? Is it an attempt at the low dose fast shots? The slightly coarser short shots? Or is it a regular shot? How did it taste?
          I don't really care about more efficient coffee making (because I only make between 10 and 20 coffees per day), I'm just curious if using a lower pressure (with coarser grind) will result in a better tasting product and I tried 5-8 bar again, my second kilo of testing.

          I got coffee that, in my opinion, tastes inferior to the finer grind and 9-11 bars of pressure.

          Both the fine grind, high pressure and coarse grind, low pressure variants of extraction sound 'right'. Increased surface area from a fine grind, more efficient/complete extraction of a coarse grind with lower push.

          I just couldn't get it to work and by that I mean I achieved a coffee that looked like a coffee and tasted like coffee however the coarse grind with low pressure variation resulted in a coffee with inferior texture. The crema of the low pressure shots were the give away, they appear anemic in comparison.

          Hope that helps.
          Again, I'm only one guy with an M7D and a single group HX, I have no tatts, no beard and no fedora -I don't charge money for my coffees either so I'll understand if my opinion doesn't carry any weight.

          Comment


          • #65
            Originally posted by Steve82 View Post
            Hi Luca,

            With the dark roast Brazil using the same grind setting and 20g dose in IMS B702TH26.5M (16 - 20g) will produce 40g in 30 - 32sec.
            At the same grind setting usually i would cut this short at 20 - 25g out in shorter time. Otherwise its unbearabley bitter and roasty, which i find people who request strong milk coffee like anyway. Even so, I would usually pull these at 89 or 90C to temper the bitter roast flavours and do not particularly find it that palatable straight up.
            I tested the last 3 quick shots at 90, 93, 95 and preferred the 95, it tasted sweeter and bolder, maybe a touch bitter aftertaste than 93.

            The 15.5g dose / quick shot ends up slightly less chewy but there's still plenty of silky coating mouthfeel with very little harsh flavours.

            So many of the ordinary cafes (around my area anyway) using run of the mill commercial/commodity dark blends could really benefit from this approach.
            Hi Steve,

            Very interesting. But did you coarsen the grind a little to get the shorter shots compared with your regular shots? That’s what Hendon et al suggest.

            Ages ago I used to basically cut off the first 2/3 of an espresso at espresso flow rates as a base for milk drinks and I quite liked that. Seemed to do a better job of maintaining distinctiveness that restrettos crush.

            I had someone over who wanted to check out the decent espresso machine on the weekend to work out if he wanted to buy one. He liked medium to darker roasts and the only one that I had on hand was a natural processed Ethiopian from a roaster I won’t put that was fairly well roasted, but left an aftertaste that I think the five people who cupped it blind with me could best describe as disgusting. Anyway, I thought the whole point of the guy trying the DE machine was to see how quickly and easily you can switch to different pressure and flow profiles, so we locked the temp the same and tried about 5 different profiles in the space of about 20 mins. From memory, I think that the 6 bar pressure profile did the best job with that coffee, making a rich and chocolatey sort of shot with a bit of fruit and also minimising the roast bitterness and sort of earthy, “whoops I left this cooked onion in a container in the fridge for two months” flavour on the back end. The question to my mind is does 6 bar improve things by making all tastes less distinctive? Or are the good ones as distinct as they are under other brew conditions?

            Luca

            Comment


            • #66
              Originally posted by BobSac View Post
              I don't really care about more efficient coffee making (because I only make between 10 and 20 coffees per day), I'm just curious if using a lower pressure (with coarser grind) will result in a better tasting product and I tried 5-8 bar again, my second kilo of testing.

              I got coffee that, in my opinion, tastes inferior to the finer grind and 9-11 bars of pressure.

              Both the fine grind, high pressure and coarse grind, low pressure variants of extraction sound 'right'. Increased surface area from a fine grind, more efficient/complete extraction of a coarse grind with lower push.

              I just couldn't get it to work and by that I mean I achieved a coffee that looked like a coffee and tasted like coffee however the coarse grind with low pressure variation resulted in a coffee with inferior texture. The crema of the low pressure shots were the give away, they appear anemic in comparison.

              Hope that helps.
              Again, I'm only one guy with an M7D and a single group HX, I have no tatts, no beard and no fedora -I don't charge money for my coffees either so I'll understand if my opinion doesn't carry any weight.
              Hi Bob,

              Good comments - very useful.

              I’m just wondering if you missed the second suggestion in the paper, which has been largely overlooked by almost everyone except Steve82. Hendon et al do propose that 6bar/15g/40g yield/15s lowers EY variability and that’s the watery shot. BUT they also propose that you can go a bit coarser and cut the shot short, as Steve tried. That should yield a shot that is very strong. Maybe even stronger than a usual espresso. That might be more to your tastes. But I don’t know what parameters you use for that. Maybe it’s like a bit coarser, 20g dose, 25g yield in 20 seconds at 6 bar. Not sure. That should be a very rich shot, which is what Steve seems to have gotten.

              Looks like your shot time in the video was close to 30s; couldn’t really tell what the yield was. So looks like you might have been making a fairly regular shot, but at 6 bar?

              Luca

              Comment


              • #67
                Originally posted by luca View Post
                Hi Steve,

                Very interesting. But did you coarsen the grind a little to get the shorter shots compared with your regular shots? That’s what Hendon et al suggest.

                Ages ago I used to basically cut off the first 2/3 of an espresso at espresso flow rates as a base for milk drinks and I quite liked that. Seemed to do a better job of maintaining distinctiveness that restrettos crush.

                I had someone over who wanted to check out the decent espresso machine on the weekend to work out if he wanted to buy one. He liked medium to darker roasts and the only one that I had on hand was a natural processed Ethiopian from a roaster I won’t put that was fairly well roasted, but left an aftertaste that I think the five people who cupped it blind with me could best describe as disgusting. Anyway, I thought the whole point of the guy trying the DE machine was to see how quickly and easily you can switch to different pressure and flow profiles, so we locked the temp the same and tried about 5 different profiles in the space of about 20 mins. From memory, I think that the 6 bar pressure profile did the best job with that coffee, making a rich and chocolatey sort of shot with a bit of fruit and also minimising the roast bitterness and sort of earthy, “whoops I left this cooked onion in a container in the fridge for two months” flavour on the back end. The question to my mind is does 6 bar improve things by making all tastes less distinctive? Or are the good ones as distinct as they are under other brew conditions?

                Luca
                Hi Luca,

                here are the results from some more testing, (likely my final round for the time being) where I attempted to put a little more method to my madness!

                BDB + Niche
                Shot temp 93C
                Where Pre infusion (Pi) is used, it is for the ENTIRE SHOT TIME to get the lower pressure / flow.
                IMS B702TH26.5M (16 - 20g) all with pedantic WDT puck prep and "The Force tamper"
                Stock medium blend (2:20 Dev time, 11minish Roast) Brazil / Guat / Indo / Eth
                All shots were pulled into little shot jugs, stirred then small amounts transferred to identical cups marked with letters underneath, mixed up / semi blind tasting.

                Dialled in Shot1 :20g dose / 40g out / 30 sec with Pi off / 8.5 bar giving standard looking espresso porn naked pour.

                Shot2: 20g dose / 40g out / 32 sec with Pi set to 76% giving 6.5 - 6 bar

                Shot3: Change grind 1 3/4 dots coarser on Niche
                Pi set to 88% giving 6 - 5.5 bar
                16g dose / 32g out / 15 sec

                Shot4: No grind change from previous
                Pi off / 8.5 bar (only hit 8 bar and dropped to 7)
                20g dose / 40g out / 20 sec

                Shot5: as per previous
                20g dose / 50g out / 23sec

                Shot6: No grind change from previous
                Pi set 88% giving 6 - 5.5 bar
                16g dose / 40g out / 17 sec


                Shot1 : Big body, more intense flavours and aromatics, lingering mid level bitterness in aftertaste, somewhat unbalanced.

                Shot2: Flat, muddy, acidity lifeless, bitter aftertaste.

                Shot3: Acidity is much brighter / prominent, matched by juicy sweetness (or wet mouthfeel), low body, softer / much cleaner aftertaste.

                Shot4: No sweetness, harsh acidity, very dry / hay like.

                Shot5: Like 4 but slightly more tolerable.

                Shot6: Lots of sweetness, a bit weak with some bitterness in the finish.


                The results make sense to me for how I have designed and roasted this blend = for 1:2 shots with lots of body, still a bit of fruit with some medium brown caramelization.

                As you and others have alluded to here and elsewhere for home baristas with good quality gear and pedantic puck prep habits who enjoy there heavier / more intense shots they are likely not going to need / want to change things unless they have a desire for exploring different taste outcomes with different coffees.

                The lower dose / fast shots most definitely will require espresso machine calibration, dialling in and fine tuning for the Barista Determined Tasty Point. But if implemented correctly I can only see benefit for most cafes...unless the cafe has a high turnover of espresso only drinkers who are used to 1:2 standard 9 bar shots? Unicorns?

                Comment


                • #68
                  Nice, and very interesting work Steve...

                  Mal.

                  Comment


                  • #69
                    Agree nice work Steve, worth experimenting if you have the equipment, rather than just dismissing this work out of fear, ignorance or laziness! You results are patterning similar to the experiments with a conical burr, different to the EK43 flat burr in the experiments.

                    I just watched the James Hoffman video on this paper and I think he summed it up pretty well and also re-ran the experiments while testing TDS with a refractometer. Jame's also observes that the espresso is a bit weak/diluted but with milk it should stack up pretty well.

                    Also I wonder on both of you move to a smaller VST basket designed for 15 gram weight if the taste/extraction will improve? Maybe too much headroom in the larger basket with a small dose is affecting the shot negatively. But still shoot for 15 grams in / 6 bar and 40 grams out.

                    Comment


                    • #70
                      Originally posted by roosterben View Post
                      dismissing this work out of fear, ignorance or laziness!
                      Nothing to do with any of the above that failed to pique my interest Ben.

                      I simply fail to see how pfaffing around experimenting with a process I know won't suit my palate is of any interest or value to me.

                      Comment


                      • #71
                        Hey Yelta, this definitely wasn't directed towards you, I respect your opinion highly and did't mean to offend anyone, although I can see my comments were fairly strong. In coffee terms/journey I am still a relative newbie.

                        I probably put myself in the lazy category as if I had a pressure profiling machine I probably wouldn't do the experiments as I am not patient or organised enough anyway. I like really strong double shots with milk and only probably go through 200 grams of coffee per week at home so also I don't see myself changing my workflow based off this paper.

                        It was more directed at the people dismissing it out of hand as some sort of conspiracy to save on bean costs or saying the science is bullshit around which I have seen a few comments here and on home-barista. The science does have a few questions around the model under different flow rates, different burrs/geometry and as many have pointed out how to rate the low pressure extractions for taste.

                        But I am quite curious as to where it leads.

                        Comment


                        • #72
                          Originally posted by SanderP View Post
                          Does anyone know when 9bar became the standard?

                          I believe they initially tried 12 bars, but found the process repetitive, and time kept dragging on.

                          Comment


                          • #73
                            Originally posted by roosterben View Post
                            Hey Yelta, this definitely wasn't directed towards you, I respect your opinion highly and did't mean to offend anyone, although I can see my comments were fairly strong. In coffee terms/journey I am still a relative newbie.

                            I probably put myself in the lazy category as if I had a pressure profiling machine I probably wouldn't do the experiments as I am not patient or organised enough anyway. I like really strong double shots with milk and only probably go through 200 grams of coffee per week at home so also I don't see myself changing my workflow based off this paper.

                            It was more directed at the people dismissing it out of hand as some sort of conspiracy to save on bean costs or saying the science is bullshit around which I have seen a few comments here and on home-barista. The science does have a few questions around the model under different flow rates, different burrs/geometry and as many have pointed out how to rate the low pressure extractions for taste.

                            But I am quite curious as to where it leads.
                            No offense taken Ben.

                            However I am one of them that reckon its all an exercise to improve the bottom line, there's been quite a bit of comment in various scientific publications as well as the internet, each and everyone touches on the economy factor.

                            Comment


                            • #74
                              Originally posted by Yelta View Post
                              ...pfaffing around experimenting with a process I know won't suit my palate...
                              But how can you be sure if you haven't tried it?

                              Comment


                              • #75
                                Originally posted by noidle22 View Post
                                But how can you be sure if you haven't tried it?
                                Does it really matter in the world scheme of things if a concept fails to float my boat? I suspect not.

                                I'm quite certain the scientific world is not holding its breath awaiting my nod of approval.
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