This week’s question is about brewing parameters: “does the temperature affect the level of solubility? If so, should we change the brewing temperature for each individual origin?”
When I relayed the second question to Derrick (our Accounts Manager and Educator extraordinaire), he said “no. no. NO. no.”
I will agree with him but allow me to more judiciously provide an explanation. In “Modelling of coffee extraction during brewing using multi-scale methods”, the authors state, “the intimate contact of water with roasted coffee solids is the cardinal requirement for producing a coffee beverage” (Moroney, et al. 2015). The process is simple: extraction or leaching occurs through the “transfer of solutes from a solid to a liquid” (Ibid). The variables become the complex factors because they include the interdependent “brew ratio, grind size and distribution, brewing time, water temperature, agitation, water quality and uniformity of extraction” (Ibid).
All of these elements effect extraction. If you change one, it will affect the rest. Accordingly for the best cup, lock-in as many as possible. Water quality has an enormous impact on the flavour of coffee but with a reverse-osmosis or BWT bestmax premium system, you will have the proper chemistry to pull the right volatile components. For more on water, see Christopher Hendon and Maxwell Colonna-Dashwood’s great book, Water for Coffee.
Brewing time and agitation will be determined by the individual machine and akin to water chemistry, there are ideal parameters but changing these brew-to-brew will have little benefit. Here we arrive at temperature. The most frequently cited brewing temperatures will land between 195 and 206 F. Anything above this threshold approaches boiling, which will extract some undesirable elements. Anything below that lower limit will simply prevent any level of effective brewing. Since you will lose a few degrees from boiler to spray-head to slurry, we recommend setting your machine or kettle to 205 or 206.
Eliminating these other components leave us with brew ratio, grind size, and uniformity of extraction. The latter will be dependent on the former. Given the focus on development in our single origin filter roasts, the golden ratio should be 1 part coffee to every 16.5 parts water. I love Matt Perger’s coffee compass for dialing-in but the reliance on changing dosage is symptomatic of underdevelopment. With less volatile compounds in the roast to move from solid to liquid, you need more coffee. Not an issue with Cut.
Finally, we are at the end of that list with only grind size remaining. I profile each coffee to represent origin. This means slight variances in roast degrees. Compounded with the differences in varietal, density, moisture content and climate, each coffee requires a specific grind. I could roast for a ubiquitous level of solubility ensuring a universal setting but that would be a disservice to the possibilities of origin.
tl;dr: Change grind? Yes. Change anything else? To again quote Derrick, “”no. no. NO. no.”
(Image from François Truffaut’s Fahrenheit 451)