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Thunguri, a town containing the factory that produced this zesty Kenyan coffee, lies just over the border inside Kirinyaga county, a mile or so from the Nyeri border.
In all, four of Kenya’s counties converge at the peak of Mt. Kenya: Embu, Kirinyaga, Nyeri, and Meru, each well known for growing some of the country’s finest coffees. Mt. Kenya stands tall in the backdrop of the coffeelands; it is Africa’s second highest peak after Kilimanjaro in Tanzania.
This coffee was grown by smallholders organized around the Thunguri factory, a member of Rumukia Farmers’ Cooperative Society, itself part of the larger Kenya Cooperative Coffee Exporters. Royal buys much of our coffee directly through the KCCE, a vast, farmer-owned network that ensures greater traceability and better profit margins for farmers than the traditional auction coffees.
Pretty standard looking Kenyan coffee here; this Thunguri coffee is graded as a AA, so about 90% of it falls between screens 18-19. It’s fairly dry with a steady water activity and a surprisingly low density compared to similar high grown African coffees. It’s possible it could be a little fragile in the roaster, or prone to scorching, as a result, but it should hold up well as green coffee in storage.
Built on common Kenya cultivars, this lot includes SL-28 and SL-34, produced by Scott Laboratories in Kenya in the 1930s. Regarded as the best of the SLs in terms of quality and resilience, both varieties are Bourbon derivative cultivars, though from different lineages: SL-28 was developed from a drought-resistant variety originally cultivated in Tanganyika, a territory that makes up part of modern day Tanzania; it’s generally considered to be of the highest quality but is not very productive compared to other commercial Arabica varieties. SL-34 is a Kenyan mutation originally found near Kabete, and excels at lower elevations. Both of these SL variants exhibit bronze-tipped leaves on the newest growth.
Joining the classics are wo relative newcomers. Ruiru-11 was developed in the mid-1980’s as the result of attempting to make an SL-28 more productive and resistant to Coffee Berry Disease and Leaf Rust by crossbreeding with varieties as disparate as Sudan Rume (for quality) and Catimor (for disease resistance), among others. For the newest release, Batian, the Coffee Research Institute retraced the steps to creating Ruiru-11, attempting to improve cup quality without compromising disease resistance. Since 2010, Batian has trickled into production. It’s named for Mt. Kenya’s highest peak, in turn named for a prominent Masai leader.
Kenya season is always a delicious time for any coffee roaster. I decided to use a shorter profile to highlight the acidity to really see the full potential of this coffee. I started the roast with a lower charge temperature and then forced the lower turning point, while also decreasing the fan speed until yellowing began. All the while my heat profile mirrors more roast profile. After yellow, the fan speed increases so that the highest speeds are used during the time when the coffee is creating the most smoke. This is done to remove smoke from the roasting chamber quickly.
First Crack was slightly late in this roast, which was surprising, but with 55 seconds of post crack development time I was not concerned with the roast tasting underdeveloped. On the cupping table the coffee had the vibrant grapefruit acidity that you expect from a great Kenyan coffee and was very sweet with black currant. The acidity and sweetness of this coffee were in balance and very elegant.
I started the roast with a moderate temperature of 367F and added heat after turn around at the peak of the rate of change spike.This provided me with a shorter roast profile to highlight the elegant acidity of this coffee. With the Ikawa roast cracking late, I was surprised to hear this coffee cracking so early at 390F. Catching me off guard, my rate of change at 9.2 was a few degrees higher than where I wanted to be. With a couple of reductions of heat I was able to extend the post crack development time to 1:14 and finished the roast with a temperature of 402F.
On the cupping table this coffee was classically Kenyan with big fruit flavors and a full body, but lacked some of the grapefruit acidity of the Ikawa roast earlier. If I was to roast this coffee again, I would use a more gentle curve with less heat in the beginning and give the coffee time to develop more organic acids during the Maillard stage which would also push first crack further back in the roast. The end would result in a slightly longer roast and more control going into post crack development.
This week, I had the pleasure of using some working coffee roast logging software for the Quest M3s! After many trials and different setups, I found a system that works. For these roasts, I used a simple K Type thermocouple in the default BT position, just below the trier on the M3s.
For my initial warm up, I still leave the back open to speed up the process. However, for the next few roasts I am leaving the back closed from the beginning of the roast cycle in order to introduce the slightest bit of airflow from the outset.
I also used higher charge temperatures (as read by the BT probe) this week: 390F. This added heat at the beginning of the roast cycle didn’t alter my turning point very much at all. Turning point time was within 5 seconds of last week’s roasts, and turning point temperatures were on average 15F warmer.
Starting off at 9.5A power and the back of the roaster closed to engage slight airflow, my plan was to get a bit more Maillard development from this coffee while compensating for the wider screen size distribution and the very slightly higher moisture content as compared to the previous Kenyan Crown Jewel.
Most likely because of this screen size distribution, the coffee heated up just a smidge more quickly. I increased fan speed to 2 at 210F/0:45, but turning point happened nearly the same time as the previous roast at 197F/1:12. This coffee did not lose momentum, even with my adjustment.
Seeing this, I knew that I would want to increase my fan speed earlier to focus on getting more Maillard development – perhaps even a 1:1 ratio between drying and Maillard. I increased fan speed at 325F/5:30. As you can see below, I nearly achieved the 1:1 ratio, but the adjustment could have been just a touch earlier. Live and learn.
I decreased heat application at 350F/6:45, halfway expecting this coffee to crack at a slightly lower temperature just like CJ1235. Turns out I should assume nothing, as this coffee cracked at a more standard 385F/8:40. I waited 30 seconds to max out the fan speed and pull chaff to the back of the roaster, and dropped the coffee at 394.2F/10:02.
This Kenya from the Rumukia Coopertaive is packed full of flavor and complexity, not to mention a high acidity kick. I had a feeling that my standard Kalita recipe was going to lead to overly high extraction, so I started by grinding Jen’s probat roast at 8.5 on my EK 43, a half notch coarser than my usual starting point. At a 1:16 ratio, this AA presented sweet notes of brown sugar and raisin balanced by plum and grapefruit acidity and just the slightest hint of sun dried tomato, often a hallmark of Kenyan coffees.
These roasts were more than 10 days old by the time I brewed them, so although I had reached a relatively high 1.46 TDS in my first brew, upon turning to Evan’s Quest roast I decided to get a little more experimental to see what a higher extraction might create in the cup. Using stage 2 on the December dripper, I was able to ensure full saturation of the grounds during the bloom phase by controlling the flow rate. After one minute, I opened the December up to Stage 3, the fastest flow rate setting, and continued to brew normally using 100g pulse pours. This brew took a little bit longer despite my shortened brew ratio. I suspected that a shorter brew ratio might created a more balanced brew, and I was right: this second cup had some delightful vanilla, brown sugar, and molasses sweetness that made a great counterpoint to the lemon-candy and tamarind acidity. If you’re looking for a classic and truly delicious Kenya, this is the choice!