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A-to-Z Intro
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Anatomy of American Espresso
by Dr. Joseph John
Although its origin lies overseas, espresso has captured North American consumers'
fancy over the last 20 or so years. One cannot walk two blocks in any city in
the U.S. or Canada without passing a coffee store or café that claims to make
espresso. Espresso and its milk-based cousins—cappuccino, latte—are everywhere.
But espresso connoisseurs familiar with Italian caffe complain
that more than 95 percent of the espresso in North America is poorly made, and,
in fact, undrinkable. Instead of being the essence of coffee it is supposed to
be, the average espresso is weak, watery, bitter, burned, without aroma, unpleasant,
and generally unsatisfying.
Over 95 percent of espresso beverages consumed in North America
are milk-based; this alone seems to justify bad espresso. The addition of milk
and syrups, however, may hide bad espresso, but they don't make it better. Imagine
how much more flavorful a latte would be if the underlying espresso tasted better.
Definition of Espresso
Original Italian espresso is about one ounce of a dark, smooth, heavy-bodied,
syrup-like, aromatic, bittersweet coffee drink topped with a thick, reddish-brown
foam of tiny bubbles. It is not just six times stronger than a cup of coffee,
as may be implied by the smaller volume; the foam, or crema, that captures the
intense coffee flavors is as important as the liquid coffee underneath.
In more technical terms, espresso is a colloidal dispersion produced
by emulsifying the insoluble oils in ground coffee. These oils don't normally
mix with water. But under intense pressure (9-10 bars) generated by commercial
espresso machines, oils are extracted from ground coffee, formed into microscopic
droplets, and suspended in liquid coffee concentrate. If strong coffee was all
that was required, using less water in a drip brewer in place of costly espresso
machines would do the trick.
It is this emulsification of oils that distinguishes the espresso
from strong coffee. It markedly alters properties of the beverage in terms of
its mouthfeel, density, viscosity, wetting power, and foam-forming ability. Volatile
vapors produced during espresso extraction hold coffee's aroma and are captured
in tiny bubbles of the crema. These aroma molecules, later released in the mouth
as espresso is consumed, find their way to the nose through the pharynx. These
oil droplets also attach themselves to the taste buds and slowly release volatile
compounds until after the espresso is long gone.
This is why the crema is so critical. If there is no crema, the
oils in ground coffee have not been emulsified, and, hence, it is not an espresso,
but merely a strong coffee. Crema, therefore, is the most critical indicator of
a well-made espresso. And rightly so.
What is remarkable about a properly made espresso is that the maximum
flavor is extracted from ground coffee while much of the caffeine and excess acids
are left behind. The high pressure at which extraction is done and the small volume
of water passing through ground coffee account for this feat.
Commercial espresso machines deliver to the portafilter a measured
amount of near boiling water at a pressure of 9-10 bars. If coffee in the portafilter
is coarsely ground and/or loosely packed, water will gush out in a couple of seconds
without extracting enough solubles from the coffee. By grinding the coffee finer
and packing it tighter in the portafilter, flow is impeded and water is forced
into the coffee particles to extract more of the soluble materials. The resulting
strong coffee takes about 15 seconds to produce.
When coffee is ground even finer and packed still tighter, the
process is slowed further. Hot pressurized water penetrates the interior of coffee
particles and spends its energy driving out minuscule oil droplets in addition
to extracting the solubles. This produces a real espresso. In this process, hot
water dissipates most of its energy in the ground coffee and has to ooze out of
the portafilter under gravity. It takes roughly 30 seconds for this extraction.
If the process takes much longer, water spends more time in contact
with ground coffee and causes undesirable acids and caffeine to go into the solution,
producing an overextracted, bitter espresso. If dosing and packing is held steady,
the "shot time" is a practical way of monitoring the extraction process. The fineness
of the grind controls the shot time.
What Is Wrong With North American Espresso?
Much of the blame falls on improper or inadequate training of the barista, the
person working behind the espresso counter. Other contributors to disappointing
espresso quality include poor choice of coffee beans, improper roasting and blending
for espresso, stale coffee beans, incorrect grinding, dosing, and packing of the
portafilter, and a limited understanding of the percolation process. Of these
the most serious errors are made in the final processes—the grinding, dosing,
packing, and extraction—that occur in the retail environment. Unfortunately,
this is also where most consumers are learning about this new, somewhat foreign,
beverage.
In most cases, baristas do not grind coffee fine enough nor tamp
it with sufficient force, thus allowing water to gush through the ground coffee
in less than 15 seconds and often as quickly as seven seconds. Coffee so produced
is watery and no oil is emulsified. Worse yet, if shots are made that quickly,
all blends, regardless of their quality, yield equally undrinkable "espresso."
North American baristas also err in another important way by running
too much water through the grounds, making espresso diluted, watery, over-extracted,
and bitter. Instead of offering the aromatic essence of coffee in a ristretto,
with lots of flavorful crema, the barista caters to the consumer who prefers the
watery version, believing that "bigger is better."
Coffee chemistry is counterintuitive. The sweet, desirable components
in ground coffee are highly soluble in water and are extracted by the first ounce
or so flowing through it. Running additional water through the same ground coffee
does not extract more coffee flavors; there is not much remaining there to extract.
Less-desirable components, such as bitterness, caffeine and acids,
are not as soluble in water, and only a small portion is extracted by the first
ounce. Running more water through the grounds extracts more of these undesirable
components. Surprising as it may seem, strong, syrupy espresso is sweet, and the
diluted, watery version is bitter.
Making the Perfect Espresso
If a majority of baristas are now doing it incorrectly, is there a better way
to produce quality espresso? Yes indeed! The prescription is actually quite simple.
Dose and pack the portafilter exactly the same way every time and adjust only
the fineness of the grind to maintain a constant extraction time of about 30 seconds.
Details follow.
Once each day, make sure the espresso machine is functioning properly,
dispensing a little more than 2 oz. of water (for a double shot) at a temperature
of 195-200 degrees Fahrenheit and a pressure of 9-10 bars. Portafilter baskets
designed for single espresso shots seldom function properly, so I recommend using
the "double basket." Ensure your grinder burrs have sharp edges to finely shave
the roasted beans instead of crushing them. Grinder performance is very critical.
Periodically rinse and season the portafilter by running hot water
through it when empty to reach operating temperature, then wiping it dry. Dose
and tamp the basket as described below and draw an espresso. Discard this "seasoning"
shot. Thereafter, it's not necessary to rinse the portafilter after each shot;
wipe it clean and dry it with cloth or paper.
Now you need to adjust the grind. Start by choosing a grinder setting
and grinding enough beans to flush out the previously ground coffee in the chute.
Discard. Do not use the doser for these initial settings. To conserve test beans,
grind just enough coffee to fill the portafilter basket. You may have to pull
the doser handle many times to get all the ground coffee out of the doser hopper.
Dose coffee into the portafilter up to the rim using a wooden or
plastic spatula to shave off the excess. If the basket is properly designed, ground
coffee in the double basket will be about 14-18 grams. Following an initial light
tamp, tap the portafilter once to dislodge all loose ground particles. Pack the
grind to the same force every time—between 30 and 50 lbs.—and, if necessary,
use a bathroom scale to measure. Pack it with a final twisting motion of the tamper
to polish the ground coffee surface.
For machines with a preinfusion cycle, the first droplet should
appear 4-8 seconds after the switch for a "short double" is turned on. Watch the
pour; it should ooze out like warm honey, not gush out like water. Turn off the
switch as the brew turns lighter, indicating overextraction. Time the length of
the pour from the moment you turned on the switch.
Adjust the grind until it takes about 30 seconds to deliver the
espresso shot. If the shots take less than 30 seconds (from the time the switch
is turned on), the grind is too coarse and needs to be made finer. If it takes
longer, the grind is too fine and will have to be made coarser.
It is not uncommon to have to adjust the grind setting four or
five times a day, depending on location and weather conditions. Make these adjustments
slowly, one step or notch at a time. Each time remember to discard the ground
coffee in the chute, grinder and doser hopper.
The doser may be adjusted to dispense the correct amount of ground
coffee, 7-9 grams for a single shot and twice that for a double. Unfortunately,
for the doser to work properly, the ground coffee hopper has to be half-full.
This is acceptable during busy times when ground coffee is used up in minutes.
During slower periods, grind only enough beans for each order.
Choosing an Espresso Blend
Most retailers do not roast or blend their coffees and are dependent on a wholesale
roaster to supply espresso blends for their use. It's important to purchase fresh-roasted
beans every week and buy only a week's supply at a time so they are always fresh.
The roasting date must be stamped on the bag so the freshness is obvious.
If the roaster believes that beans have to be dark-roasted and
oily to be in an espresso blend, look for a different roaster. This shows a limited
understanding of coffee bean characteristics and even less about espresso.
If the average espresso extraction time for a retail store is less
than 20 seconds, all shots will be watery and bitter, and a higher-quality blend
isn't going to make a difference. A cheap blend will suffice; no reason to waste
money.
However, if you make the effort to produce a proper espresso, you
should select a blend that is consistent with the quality of espresso the customers
deserve. Check the blend's performance drawing actual espresso (making brewed
coffee to test espresso beans is a meaningless exercise). The physical properties,
such as color, body and crema, and the flavor characteristics, such as aroma and
taste, must be appropriate and in proper balance. Most blends focus entirely on
flavor and perform poorly on color, body and crema. The flavor should be clean
and well defined from a single coffee or two, built on a muted base.
The crema should be reddish brown, velvety, plentiful, rich, and
persistent, lasting many minutes before it breaks in the middle. Linger over the
cup as the crema releases the aroma of freshly ground coffee. Taste it straight,
without sugar or milk. Note if it is mellow, smooth and sweet, with lots of body
and low acidity (high acidity is not a desirable feature of a quality espresso).
It should contain no unpleasant bitterness and not even a hint of sourness. Check
its finish. Observe how long the aftertaste lingers in the mouth; it should be
pleasant if the experience is to be memorable.
Most retailers in North America can provide a much better quality
espresso and espresso beverage to the consumer without major investments. It takes
a better understanding of the espresso process and improved training of their
employees. That the consumer is not demanding a better espresso is not a good
excuse. As was learned in the wine industry, delicious espresso will promote coffee
drinking, and bad espresso will hurt the industry.
Dr. Joseph John is president of Josuma Coffee
Co. in Menlo Park, Calif., and designer of Malabar Gold, the company's Premium
European Espresso. He can be reached at 650/366-5453 or by e-mail at josuma@aol.com.
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