Coffeol,
or coffee oil, develops inside the bean during roasting.
Darker
roasts -- roasts that cook and surface the natural sugars in coffee making it
taste sweeter -- have been popular during the last 15 years in the U.S. with the
upstart of many of the West Coast specialty coffee roasters. The more recent
trend, however, is toward lighter, full-city roasts which offer the widest degree
of flavor among coffee varietals. This lighter roast is also more akin to
the preferences people had during the 1700s.
An
after-dinner roast is the same as an espresso roast -- a dark
roast producing a strong and rich cup of coffee.
An
Italian roast is very dark; a French roast is dark; Vienna, Full City, and City
are different degrees of medium; American, Cinnamon, and Scandinavian are different
degrees of light. The lighter the roast, the more chlorogenic acid will
remain and the more bitter the coffee is likely to be. Medium roasts generally
bring out the acidity in the bean providing for the most flavor.
During
the roasting process, carbon dioxide is created within the bean. The carbon
dioxide protects the bean against oxidation. As the carbon dioxide content
of the bean diminishes over time, there is more opportunity for oxygen to attack
the aromatic oils in the bean. When coffee is ground, much of the carbon
dioxide is released and the surface area of exposure to oxygen increases.
This speeds up the oxidation of the oils, and the coffee becomes stale more quickly.
Flavored
coffees are sprayed with flavoring after roasting and being cooled to near 100°F.
At this temperature, the beans are more porous and will absorb the flavoring.
With
a lighter roast, you get a more acidic, distinct taste; with a darker roast, more
bittersweet.
There
are different types of roasts given to coffee beans. One factor in the darkness
of a roast depends upon when the oil in the beans appears during the roast.
In general terms, the lighter roasts - a "city" and a "full-city"
roast -- are ones completed before oil appears on the beans. The darker
roasts - "Vienna," "Italian," and "French" - occur
with various stages of the oils on the surface of the beans.
A
scanning device is used by roasters to help eliminate diseased and underripe/overripe
beans before going to the roaster. This lessens the adverse taste impact
these beans would have on the final product.
Consistency
in a blend is important. Yet consistency does not mean that the same coffees
are used time after time. Coffee markets of the world fluctuate and constantly
challenge expert roasters to maintain blend consistencies with various coffees
that are available at any given time at a similar cost.
When
coffee beans cool from roasting, over 600 chemicals are released resulting in
the coffee's aroma.
The
names of roasts change with time. For example, a "city" roast
in the 1800s meant a dark roast. Now it is considered a light roast.
A "city" roast is somewhat darker than a "cinnamon" roast
which is considered the lightest roast. Neither roast has oil on the surface
of the bean. You will not, however, usually find a "cinnamon"
roast in a specialty coffee shop because of the high level of chlorogenic acid
remaining in the bean which makes the taste more bitter. Large manufactures
however will mix a "cinnamon" roast with other roasts because the lighter
the roast, the less time involved in roasting and the more bulk remains in the
bean. Thus the manufacturer cuts costs of production in two ways at once.
A
green coffee bean is about 15% oil. This oil is bound in the bean.
As roasted, the oil is released and works its way out as the roasting process
makes the bean porous. The oil appears on the surface first in dots ( a
light to medium roast), then blotches ( a medium roast), and finally a gloss (
a dark roast).
There
is no single roast that is best for all coffee beans. When beans are roasted
very darkly however, many of the oils and flavor components are forced to the
bean's surface. Oily beans lose flavor more quickly than those beans in
which more of the oils are retained within the bean as in lighter roasts.
Roasting
a coffee bean increases its size by over 50%, but reduces its weight up to 20%.
The
chemical changes that occur to coffee during roasting are called "pyrolysis."
With pyrolysis, the coffee develops chemical compounds resulting in the aroma,
flavor, and body of the coffee.
Ever
notice the one-way air valves (or "belly-button valves") on some bags
of packaged coffee? These valves first appeared in the late 1960s and allow
the carbon dioxide to be released from freshly roasted coffee without allowing
oxygen in. These valves help preserve the freshness of the coffee.
However, remember that roasted coffee loses its freshness relatively quickly.
Pay attention to the date of the roast on the bag if the packager was considerate
enough to provide one for you. More often than not, you will not find a
roast date. You can purchase fresher coffee directly from your favorite
specialty coffee shop which can also generally provide you the roast date of their
coffees for you.
During
roasting, the coffee bean produces oils at about 400º and the outer part of the
bean darkens.
Darker
roasted coffee beans are stronger and sweeter than more lightly roasted coffees.
They usually have a shorter shelf life due to the oils penetrating the surface
of the bean more. Darker roasts can mask the true flavor of beans compared
to a lighter roast that will accent the beans acidity.
In
the United States, specialty roasters generally use Arabica beans for their espresso
roasts. However, in Italy, nearly half of the beans in an espresso roast
may be Robusta beans and thus much higher in caffeine content.
The
color of the roasted coffee bean does give some indication whether or not the
acidity of the coffee will sparkle. The lighter the color, the lighter the
roast, and generally the more the acidity of the coffee will sparkle or "dance"
on your tongue.
Ever
hear of a "baked" roast? This is when the finished product has
a medium brown color on the outside, but in which much of the acids and oils have
been lost in the "smoke." This can occur when the roaster turns
off the flame during roasting to slow the roasting process but does so for too
long, or when the roaster has lowered the air temperature too much at the end
of a roast. These roasts may taste flat and are low in body.
The
general roast time of most coffee beans is 9 to 14 minutes. If a roaster
can cut these times by 3 to 5 minutes, it can greatly reduce fuel costs.
However, one can tell the difference in the taste. Either there will be
an underroasted interior or beans will be roasted at various stages due to uneven
heat transfer.
Immediately
after roasting there are two ways to cool the bean -- with air or with water.
Using water is necessary on large batches so the beans will cool quickly enough
to not burn the roast. Using water, however, is controversial.. If not done
in just the right amount so all the water will evaporate, some of the water will
be absorbed by the bean which will open the pores and allow valuable flavors to
escape.
A
lighter roast brings out the acidity in the coffee bean. The acidity is
what gives the bean its life, sparkle, and complexity. As a bean continues
to be roasted, the caramelized sugars emerge adding body, but the acids diminish
and are lost forever. A truly sophisticated coffee drinker will learn to
appreciate both the lighter roasts and the darker roasts, not one over the other.
Each roast has something special to offer.
Roasting
coffee beans changes the chlorogenic acids in the green bean into more flavorful
acids like acetic, citric, malic, and formic.
Flavoring
roasted beans is a simple process. After they are cooled, they are mixed
and stirred with a flavor extract in a metal barrel to coat them with the liquid.
Much
of the quality of a coffee depends upon the roaster. A quality roaster needs
to be an artful engineer with good instincts and skills. Much of the enjoyment
you experience from drinking a good cup of coffee or espresso depends upon the
talents of the roaster.