Barista Magazine

DEC 2017-JAN 2018

Serving People Serving Coffee Since 2005

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29 and a ramp-down profi le tames the shot. If you refer to the information gathered from the scientifi c report toward the beginning of this article, you'll see that this general methodology seems to agree with the results. If polyphenols are responsible for at least some of the bitterness and acidity in espresso, controlling the presence of them will have an impact on fl avor balance. Specifi cally, a ramp-up temperature profi le has been shown to increase their presence by close to half, and a ramp-down reduces their presence by about a quarter, according to the study. Although, for now, much is unknown about how each specifi c chemical compound in coffee affects the overall fl avor profi le, utilizing a tool that can uniquely change the rate of extraction for groups of compounds is very useful for balancing the taste of espresso. Being able to dynamically fi ne-tune extractions using a variable as infl uential as temperature is helpful when reacting to daily changes experienced behind the bar with water-chemistry variance, atmospheric differences, and changing coffees. Hopefully the information detailed in this article can be used to better understand what temperature espresso experiences in an extraction and how Temperature Profi ling technology could be used to dial-in espresso. Experiment notes: The experiment was conducted using a Rancilio 18g laser-cut precision basket, with an 1/8-inch hole drilled directly in the center. A 0.8mm restrictor was used in the hole, through which a J-type Fluke bead probe was inserted. The probe was positioned out of the hole and against the basket bottom 1cm before making a 90° angle upwards, protruding from the base of the basket by 0.8cm, so as to be positioned in the middle of an espresso puck. For each set of experiments, it was determined that the machine needed to acclimate to its set temperature for a period of time. A set method of acclimation was not used. Generally, the temperature would be set and a full volumetric cycle would be run into the portafi l- ter with no coffee. Then, shots would be pulled and temperature moni- tored until the temperature profi le maintained consistency (typically 2–4 extractions). For each extraction, there was a downtime of two minutes, during which the next shot would be prepared. Each dose was weighed to 18g +/- 0.1g, the bed was groomed gently to be fl at, and received a brief, light, even tamp. At the 1:50 mark (time elapsed since last extraction), the grouphead was purged for three seconds, and the extraction com- menced on the 2:00 mark. —An d re w Be tti s —Andrew Bettis

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