We are in the midst of a conversation about how the constellation of choices around sourcing, roasting, and brewing will shift the possible (and probable) outcomes in your cup. It all started with a great question about metal versus paper filters that became a rant about roasting for origin, which leads us to pouring water on grounds. So! What are the dividing lines between universal and unique when it comes to brewing a cup?
One note: I am mostly focusing on filter here but there is a lot of carry-over to espresso. The difficult thing about dialing-in coffee is the sheer number of factors: bean-to-water ratio, grind size/distribution, water quality/temperature, and – to hearken back to last week – roast development. The easiest path to maximizing your cup is to decide on the roaster and lock-in the other parameters accordingly. What do I mean here? Well, if you want to use a roaster who veers towards very light, potentially underdeveloped roasts, the coffee solubility declines. Extraction will be a challenge and you need to compensate with higher ratios and/or finer grinds. Conversely, if the starting hopscotch block is a dark roast, you will find yourself jumping towards less coffee and coarser grinds because solubility increases and extraction occurs with greater ease.
Hence, roast philosophy operates as the center hub for a number of variable choices. If you are using Cut for filter, we can then lock-in this ratio:
And for temperature the best bet will be around 205°F (although, many machines probes provide poor data or have fatal flaws like colder water in the spout of a goose-neck kettle but generally this is the mark). Your water should have a good dose of magnesium and some controlled levels of bicarbonate. Adjusting that grinder with its sharp, aligned burrs is all that is left!
However, one last spiel on ratio. Dose is one of those branching lines for the universal and the unique in a coffee. If you end up with too much coffee, say a 14:1 or a 12:1 ratio, you will get aggressively strong coffee. Alternatively, drift too high into say 18:1, you will end up watery and weak. While less associated with taste (especially compared to extraction from grinding), you will have some sourness in a weak coffee and bitterness in a strong one. The best gauge is often touch or mouthfeel, with low water ratios overwhelming your senses with thick harshness; or high water ratios running away from you in a fleeting tea-like experience.
So onto the unique in dialing in and extraction! Allow me to call upon the chart on the bottom of my parameters sheet:
Any over-extracted coffee tastes bitter and produces astringent notes of roast and woodiness regardless of origin. Equally, any under-extracted coffee will hit you with sour and salt despite its country, growing conditions, or processing.
It is in interesting that when it comes to roasting, there is not much overlap between the flavours associated with under/over development, as one is raw vegetables and the other burnt dessert. Yet for extraction, you see some mixed flavours of greenness and freshness on both sides. I taste cilantro in an under coffee and broccoli stem in an over. I get the tinge of pith in under and the bite of zest in over. I even get quick finish in under and hollowness in over. I think that is why many in the industry conflate the two and end up grinding the wrong way when trying to fix a cup.
So hopefully, this is starting to add up with development coming from roast combining with strength from dose/ratio and extraction from grind setting. I will forever recommend Matt Perger’s compass (available here) for insight into this interconnected web and, as always, trust your palette!