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 andonline auction program.
can i re roast coffee beans, 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 moreabout 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 numberfrom zero, representing a minimum but notquite fully off fuel setting to 100representing my highest fuel setting. i also have air flow controlmanipulations 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 morecontext.
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 onthe final flavor of the coffee as long as we avoid introducing roasting defects. with this coffee i expect to be roasting batches atbetween one-third and one-half capacity and the roaster has enough power atthose 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 toodark, 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 finda 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 offlavor is reduced. the fourth cup is starting to get a little bland and by the fifth cupthose 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 thiscoffee it's just a thin the bland coffee withnothing interesting about it i continue tasting at least the bettertasting 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 likethe 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 muchsmoother and that's just because i
have much better data acquisitionhardware connected to my production roaster while i don't have fuel settinginformation on this machine i do have a second thermocouple for air temperature and i also have the rate of change of the bean temperatureplotted automatically. those aren't shown here asthey aren't very interesting but they do make it much easier to make appropriate control changes whenreproducing this in future batches.
comparing this against the first test batch we can see that from the start of color change from green to yellowthrough 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 idon't hear that in the roasting drum but there are acouple pops in the cooling bin. interestingly with a slightly longer amount of time before the color changefrom green to yellow the total roasting time for this batchcompared with time to the same temperature from myfirst test batch is almost exactly the same but there is a considerable difference inhow these coffees taste. one the test production batch has had achance 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 greaterintensity of flavor which is what i intended with that change in how thecoffee was roasted. the aroma of the brewed coffee is alsofantastic the lemon characteristic from the first
development batch has been replaced witha much more interesting grapefruit taste. overall i am extremely pleased with howthis coffee has turned out.
this is good.
