In my last article for “9 Bars,” I wrote about the differing
philosophies in espresso extraction. The Italians are very precise in
their method: 15 grams of espresso plus or minus a gram, while many
American roasters and retailers prefer to extract with at least 20
grams, where the puck is large enough to touch the group screen. There
were, and are, many intense debates about this, and my advice then was
to play and come up with your own method and not fall into a certain
methodology “just because.” Well, I have taken my own advice and would
like to share a little about what professionals are figuring out about
the extraction process.
Before I dive into this ever-growing theory, I would first like to
bring up two remarkable trends that have come to pass in the last year:
The bottomless portafilter and the growing preoccupation with
single-origin (SO) espresso.
The Bottomless Portafilter
You may or may not be aware of the latest tool in the barista’s
toolbox. Basically, what many have done is machine the bottom of the
portafilter off so that the basket bottom is exposed. This allows the
barista to grind, dose, tamp and watch the extraction process
first-hand without a chunk of brass in the way. If all goes well, many
droplets of oil ooze out the basket bottom simultaneously, and as the
basket begins to bow under the massive pressure (9 bars), the espresso
pools together at the bottom center of the basket and pours in one
column. Any unevenness in your tamp or puck distribution will be
evident in the bottomless portafilter. The column of espresso will pull
to one side of the basket and extract there first, resulting in the
over extraction of that side and the under-extraction of the rest of
the puck. If you have ever pulled a double shot with spouts and noticed
the stream pulling on the left or right, only eventually pulling from
the other spout, you have witnessed an uneven extraction. This goes for
shots that seem to pulse from light to dark as well. The over-extracted
(blonde) espresso mixes with the under-extracted (dark) espresso and
creates a funny-looking pour. So now with the bottomless, baristas can
watch their extraction and troubleshoot their technique.
Different Coffees, Different Extractions
Now for philosophies on single-origin espresso. Many people are
advocating the use of coffees from single farms and forsaking the
tradition of using a blend for espresso. What this does is provide the
imbiber with the experience of that bean in all its glory and possible
shame. Most often the espresso will not be well-rounded in flavor, but
rather one-sided and intense in regard to that flavor. Nonetheless, it
can taste better than a blend, but for different reasons. And even if
the coffee is not pleasing to your pallet, its uniqueness is worth the
try.
At The Albina Press, we have a dedicated grinder for SO espresso, and
we rotate coffees in and out every week. One week we thought it would
be great to pull an Ethiopian Harrar as an espresso (most commonly
known for its wild, sometimes intense blueberry flavor). The coffee was
roasted locally by Stumptown Coffee Roasters and is semi-washed. This
gives the coffee fuller body due to more soluble matter imparted to the
bean during processing. Washed coffees tend to be complex and clean
while naturally (or dry) processed coffees are heavier in the cup. What
the latter loses in complexity it makes up for in intensity.
Our first time running the Harrar through the machine, we dosed as we
would the Hairbender Blend (Stumptown). The blend is almost entirely
composed of washed coffees and a little bit of semi-washed. With the
Hairbender we dose fairly high, around 20 grams for a double, and cut
the stream at just under two ounces in 22 to 27 seconds, depending on
the coffee’s age. We turn off the pump the moment the coffee begins to
“blonde” and loose viscosity. With the Harrar, our pours lasted well
into the 30-second range. The pour just kept going … no blonding, nor
anything that would be indicative of over-extraction. The empirical
evidence made me think that certainly not all coffees are created
equally in terms of possible solubles. The Harrar (due to its
processing method, I’m guessing) had more to give than the blend. In
fact, we could dose in the Italian fashion (15 grams) and come out with
a tasty shot. Hmm … maybe the Italians were on to something.
When we then tried pulling a fine coffee like the Guatemala San
Vincente or any other high-grown washed coffee, a lesser dose would
have been suicide for the origin. It really just seems that the washed
coffee didn’t have enough to give to the cup. At about 18 to 20
seconds, the coffee would cry out for us to end its suffering. If we
upped the dose, however, the shots flowed like honey and produced what
we know to be a great espresso.
It would seem, then, that both the Italians and the Americans are
right. I say this because Italians will typically use dry-processed
naturals and maybe even a little robusta in their blends that would
facilitate a lesser dose for extraction, while their American friends
tend to use more washed coffees, many of which wouldn’t touch a robusta
for their life. This would explain the trend to dose more. Doesn’t this
make so much more sense now?
While mulling over this theory, another coffee fanatic named Chris Tacy
enlightened me with even more theorizing. His idea is that
dry-processed natural coffees tend to be more hydrophilic than
high-grown washed coffees. The Merriam-Webster Dictionary defines
hydrophilic as “having a strong affinity for water.” Tacy’s experience
is that naturals will need to expand more in the brewing chamber due to
their ability to absorb water, and unless allowed to do so, the puck
will rise and can crush the group screen. The washed coffees, however,
really won’t absorb any water and don’t expand near as much. This would
explain the need for the several-millimeter clearance in the brew
chamber that both Andrea Illy (in Espresso Coffee: the Chemistry of
Quality, Academic Press) and David Schomer advocate. A largely washed
blend using this method results in a soupy mess left over in the basket
after brewing.
After all this fussing around, I am left with the conclusion that there
may be a right and a wrong way to pull a blend or a single-origin
espresso, but it is based on the components of the coffee and not just
regional preferences. I think it is safe to say that if your blend is
composed of naturals and maybe some robusta, give the coffee room to
grow. But if you have a washed blend, dose a little to a lot more or
else you will struggle with early over-extraction and a thin,
astringent cup of espresso.
And by the way, what’s in your blend these days?
Billy Wilson is a manager at The Albina Press in Portland, Ore. Comments on this article may be sent to
