I recently brought in
a new lot of coffee from Hama cooperative in Ethiopia
I first enjoyed coffee from this cooperative
in 2005 when I purchased some that had placed
highly in a then new competition and online auction program.
The following year I went to ethiopia as one of the judges for that competition
where a coffee from Hama cooperative took the highest score in the competition
with one of the most incredible coffees I've had on a cupping table
which also sold for the highest price
in the associated auction.
Once the competition was over I was able to
travel around the country and
visit this and other cooperatives
that placed well and learn a little more about
who they are and how they work.
I'm always thrilled to be able to bring in one of their coffees.
As with every coffee I buy
I start with roasting a small batch
pulling several samples during the roast.
I'm presently using a Diedrich IR-1 lab roaster for this and this is set up
to allow me to do profile development work with
less than half as much coffee as I could with my IR-12.
With this roaster I have
some information that's logged automatically
Most importantly
bean temperature over time.
I also have
the setting on my fuel control as a number from
zero, representing a minimum but not quite
fully off fuel setting to 100 representing my highest
fuel setting.
I also have air flow control manipulations
automatically marked and as I pull samples from
the batch to cup I manually made a note of when these were pulled.
Bean temperature measurements are something that will vary among roasters
so I'm going to add in a little more context.
With the machines that I'm using
coffee will appear green until it reaches a temperature
of 300 degrees.
This early portion of the roast
in my experience has the least impact on the final flavor of the coffee as long
as we avoid introducing roasting defects.
With this coffee
I expect to be roasting batches at between one-third and one-half capacity
and the roaster has enough power at those loads that I don't need to give this
portion of the Roast much consideration.
At 300 degrees Fahrenheit
the coffee starts to change from green to yellow.
At 330 the coffee changes from yellow to brown.
at 380 degrees it's possible
to hear the start of first crack
and at 430 the coffee will be entering the second crack.
With this batch I have ten samples. Two of these were pulled
before the start of second crack, one was pulled
right at the start of second crack and the rest were pulled later.
My hope with this was that I would have samples
that are too light, samples that are too dark, and that I would find
what i'm looking for somewhere in the middle.
With this coffee I expect that I'll find
what I'm looking for
on the earlier half of these samples, something that's
either a light roast or on the lighter side
of a medium roast, but you never find a good dark roast you don't look for one.
Allowing the samples rest to overnight I cupped these coffees.
The fragrance evaluation was most favorable on the
first five cups
The aroma evaluation had the best results
in the first four cups.
The first cup isn't bad. It has a nice Lemon
lemon zest flavor, really good flavor intensity
moving darker it gets better balance, sweeter, more complex flavor
While the flavor improves
through the third cup, the intensity of flavor is reduced.
The fourth cup is starting to get
a little bland and by the fifth cup those lemon notes
are just gone.
At the 7th cup I'm starting to taste carbony flavors associated with dark roasts
and by the 8th cup all I'm tasting is roast
and that just doesn't work for this coffee
It's just a thin the bland coffee with nothing interesting about it
I continue tasting at least the better tasting cups
until the coffee is cool.
At this point I'm thinking that I can do better than any of these cups. I really like the
intensity that I'm getting
on the first two cups but I also like the sweeter flavor that I'm getting
right at the edge a second crack.
To get that I want to change how I'm roasting the coffee and focus
on that early range for the next set of cups.
yeah that's
that's really nice
but I can do better.
I went back the lab roaster, reducing the roasting
time from the transition from green to yellow through
the end of first craft and then increasing the time
from the end of first crack focusing on
the range of end temperatures where I was getting the best results on
the first test batch.
With good results on the cupping table I roasted a test production batch on the IR-12.
The graph for this batch is much smoother and that's just because I
have much better data acquisition hardware connected to my production
roaster
While I don't have fuel setting information on this machine I do have
a second thermocouple for air temperature and I also have the rate of change
of the bean temperature plotted automatically.
Those aren't shown here as they aren't very interesting
but they do make it much easier to make
appropriate control changes when reproducing this
in future batches.
Comparing this against the first test batch we can see that from the start
of color change from green to yellow through the color change from yellow to
brown
I'm roasting this a little faster.
The same in the range from the color change from yellow to brown
through the start of first crack
and in the range of first crack through the end
this is starting faster but finishing slower.
The end is
right on the edge of second crack where I don't hear that
in the roasting drum but there are a couple pops in the cooling bin.
interestingly with a slightly longer
amount of time before the color change from green to yellow
the total roasting time for this batch compared with
time to the same temperature from my first test batch
is almost exactly the same but
there is a considerable difference in how these coffees taste.
One the test production batch has had a chance to rest it's time to taste
the coffee in a way that's more representative of how a customer might enjoy the coffee.
The end result here is clean
sweet, well-balanced with a greater intensity of flavor which is what I
intended with that change in how the coffee was roasted.
The aroma of the brewed coffee is also fantastic
the lemon characteristic from the first
development batch has been replaced with a much more interesting grapefruit taste.
Overall I am extremely pleased with how this
coffee has turned out.
This is good.