One of the most basic barista tasks is also the hardest to master. Over the course of a shift, a typical barista will pull hundreds of shots of espresso. In order to pull a decent shot, the barista must evenly distribute the ground coffee in the portafilter and compress the grounds with a nice, level tamp. It sounds simple enough, but after training dozens of baristas I can attest that it’s one of the last barista skills I see people master. Although steaming milk, pouring latte art, and making pour-overs might intimidate new hires, it’s tamping that keeps a self-aware veteran awake at night. Even a minuscule inconsistency in the distribution of the coffee can result in the dreaded phenomenon of channeling. Simply put, channeling is when the water passing through the bed of espresso finds a path of least resistance. This results in a small portion of coffee coming in contact with too much water while the majority of the coffee remains underextracted. The result is a shot that is simultaneously sour and bitter with a thin mouthfeel. It’s an unpleasant sensory experience no one should pay money for.
As a barista educator who received above average tamping scores during my last couple of barista competitions, I have a confession I’m reluctant to make: I still see shots I pull channel. Of course, those shots never make it across the counter, but there’s nothing like re-pulling a shot during a rush to throw off your bar flow. That’s why I was very interested a couple of years ago when WBC technical judge Şerif Başaran told me about a barista in Australia who invented a distribution device that was so effective Başaran handed out his first perfect score on distributing. I emailed a barista who was unknown to me named Sasa Sestic, but was disappointed to hear he only had a couple of prototypes that weren’t for sale. Fast forward a year and a half later and Sestic is the reigning World Barista Champion and his Ona Coffee Distributor (OCD) is making waves in the global barista community. After getting to use the OCD for the first time at SCAA, I wanted to see if it lived up to the hype. So after getting home I ordered one from the American importer of the OCD, Brew Global.
As a working barista, I’m skeptical of any product that hasn’t been bar-tested. As such, in a slightly reckless decision I decided to use Quills Coffee’s loyal customers as guinea pigs and use the OCD for an entire bar shift. Over the course of a moderately busy closing shift I used it to distribute around 100 shots.
Immediately, I verified that the OCD makes the top of your espresso puck perfectly even. So even, in fact, one coworker didn’t realize the coffee still needs to be tamped after distributing! (I tried pulling a shot without tamping- I don’t recommend it.) There’s some debate, however, concerning what impact distributing the top of the espresso has when the majority of the grounds are below. But if you’re trying to evenly extract a shot of espresso, it’s hard to see how starting with a perfect flat surface before tamping is a bad thing.
Over the coarse of the bar shift, I didn’t have a single shot channel. In fact, in all of my subsequent use of the OCD I’ve only had one shot visibly channel on me, and I think that was due to a megadose from the grinder. (It wasn’t during a formal testing session where I double-weighed every shot.)
Third, I found it much easier to evenly tamp the grounds after using the OCD. I always check to see how level my tamp is when pulling espresso, and I believe my tamping was more reliable with the OCD than without.
Ostensibly, a more even saturation of the espresso grounds should result in both a higher total dissolved solids (TDS) and extraction percentage. As such, I pulled out our trusty refractometer and started taking some readings. I compared three spins of the OCD to my normal distribution technique (3-4 horizontal taps on the side of the portafilter with my hand).
In order to achieve as accurate data as possible, I weighed each dose to the tenth of a gram and alternated shots with and without the OCD in order to minimize the effect of grinder temperature on any one set. I pulled each shot with the same grouphead of a La Marzocco Linea PB in order to get as consistent water delivery as possible. This, however, was an extremely small data set and is nowhere close to conclusive (click here for the spreadsheet). I would love to see other people repeat the experiment (or send me more VST filters!)
Taken as a whole, the set with the OCD averaged much lower extractions than the set without: 20.45 compared to 21.37. This surprised me, as shots brewed with a naked portafilter with the OCD appeared to saturate more evenly than those without. Conversely, the spread with the OCD was smaller in every category. Although extractions with the OCD were lower across the board, shot times, strength, and extractions were more consistent.
So why was the OCD more consistent from shot-to-shot while being less effective at extracting in this data set? My guess is that it was to do with the partial tamping that happens when using the OCD on it’s highest setting (which I used for this experiment). In the process of distributing the grounds, the OCD partially compresses the puck. The barista then tamps the puck even further with a tamper. I think the single motion of my more conventional tamping technique allows for more dense compression of the puck. This would explain why the second set averaged almost an entire second longer of shot times. If I can bring myself to drop another $20 on VST filters, I would like to try the experiment again with the OCD on its lowest setting.
In addition to lower extraction percentages, I did encounter two potential problems, which were also articulated by most of the baristas I asked to give me feedback.
One, the OCD introduces another step to espresso preparation. If the device adds even 3 seconds to espresso preparation in a busy café that could easily amount to an extra half hour customers are waiting for drinks. I found, however, with proper mise en place a barista could introduce the OCD to their espresso routine in the same amount of time it takes to distribute other ways, if not less. Furthermore, I believe the OCD will make up for any potential lag with the time it will save in re-pulling channeled shots.
Two, sometimes a small amount of coffee grounds stick to the bottom of the OCD. This seems to happen without rhyme or reason, though it happens less on the lower settings. The waste was always less than .1 of a gram, but over the coarse of the day it adds up, dirtying the counters in the process. The mess is easily remedied by keeping a brush near the espresso grinder, but the waste is unfortunate. Some users online reported less cling over time, but ours shows no sign of letting up.
In spite of the aforementioned problems, I strongly recommend the Ona Coffee Distributor. The OCD all buts eliminates channeling and makes tamping easier for new baristas. My experience using it on bar and in the lab point to greater consistency from shot to shot than other distribution techniques. The OCD also makes it easier for different baristas to achieve the same results. As such, I think using the OCD increases the likelihood of serving your customers a tastier cup of coffee. If nothing else, any barista competitor who doesn’t use the OCD is throwing away tech points!