CI does the extraction factor juggle

September 2, 2006 – 3:30 pm

the sulawesi, it tasted of baked hash. maybe some newt tail. extraordinarily gritty.

thus, conjuring the notion that brew temperature is how one buys espresso solubles, the conclusion was reached that we were, ah, overpaying. that is, the extraction of oils was heavily tainted by the extraction of bean infrastructure itself — ribs and spines and ligature. this was not burnt. this was baked and dry. the thinner the swill and the more wretchedly brackish the cup results, the more plain it became that the issue was not of dose or machine anomalies. indeed, close examination revealed beans issuing from the roaster with the taint of mud on their breath.

why should you care? this was a mildly surprising development since, in the summer months, i never have problems with overly baked bean interiors of the kind to easily sell themselves for a bit of hot water. indeed, hot ambient temperatures typically force me to lengthen roast profiles to avoid fast cooking. but this discovery — that mother sulawesi had been crock-potted to death — led to a handful of clarifying barista moments.

elucidation the first: stalling interior bean temperature during the roast — which bakes dry the innards that then (a) taste like terra cotta, and (b) more easily break down under hot water pressure — is closer at hand than one thinks. in this case, the lack of meaningful chaff on the sulawesi left the chaff collector above the roast chamber mostly empty, allowing more hot air to escape the chamber toward the end of the profile. result: long gaps between first and second crack, a glaring sign that the steady temperature climb had plateaued. i should have noticed. this fine line, between a steady rate of increase and a stalled profile, demands an attentive roaster of course — particularly when using hot air. i, frankly, was not very. in fact, the evening roast period is typically when i wander off to brush my teeth. bad roast artisan. bad.

elucidation the second: the most reliable method of covering up undesireable solubles in a coffee seems to be a low dose, cooler temps and short shots. the low dose, of course, demands a finer grind, which would seem to expose MORE of the defective solubles for extraction. instead, i now believe that what’s more important (than previously thought) is the temperature of the water — and its dwell time in the espresso puck. thus, a low dose and a short shot, combined with a cool brew temp, leave the MOST amount of bad solubles in the puck while extracting the necessary oils … which are less plentiful, probably, because we’ve baked them all away. a short shot is all you’ll want!

elucidation the third: this also informs non-defective coffee extraction. with the sulawesi — and most other single-origin espressos i brew — roasted optimally, the increase in water temperature, combined with an already fine grind, is enough to extract a more rounded result. but what if the coffee is, say, rather acidic on the tongue and the goal was to apply a wee damper? then i’d go back to the low-dose, low-temp shot — but lengthen the extraction time.

this is a departure from my previous assumptions that when playing with the flavor of a well-roasted coffee, you just adjust the dose/grind see-saw until you get something that tastes good, then zoom in on the optimal brew temp. instead, i’m starting to think that the brew temp is a better slide rule by itself — and that longer-than-average shots are acceptable too. essentially, the positive traits of the coffee are there for the taking. the low dose is your clarity benchmark. why not let the water temp do the work? it’s a more valuable currency than i thought!

we should note: this blog could change its mind tomorrow.