The Aberdares Mountains erupt from central Kenya, just west of the mountain that bears the country’s name. The forested mountain range also happens to be fertile soil for coffee, among other crops, and the coffees from western Nyeri county benefit from its particular ecosystem.
This delightful Kenyan selection, produced by smallholders organized around the Aguthi Cooperative Society’s Thageini Coffee Factory, also happens to be one of our “Red Cherry” selections. In exchange for the highest price we paid for any Kenyan coffees this season, Red Cherry Project coffees undertook a number of extra steps to isolate and enhance the highest quality coffees. It’s a win-win scenario: we get great coffee, farmers get guaranteed pricing without having to wait for auction results.
Model farmers identified for exceptional performance were selected exclusively to participate, and asked to deliver only ripe cherries which undergo a secondary hand-sort visually and then a pre-fermentation soak to remove any low-density floaters before pulping. After an extended 72 hour fermentation and channel grading the wet parchment soaks for 16-24 hours in clean water. In addition to the usual hand-sorting during parchment drying, the coffee spends time under shaded tarps prior to skin drying to help prevent damage from the sun, and once the parchment is fully dried it is stored in GrainPro packaging even before transportation to the dry mill.
This Nyeri coffee is citric forward, both fruit and floral, and has generous sweetness to underpin its lively acidity. It’s an instant classic with strong notes of Ruby Red Grapefruit, lime, pomegranate, and blackberry; a Kenya-lover’s Kenyan coffee, to be sure. Enjoy!
Back to some pretty normal looking numbers in terms of green grading this week, this Nyeri coffee checks most of the usual boxes: low moisture content and water activity and classic AA grading at 95% 18 and up – very large beans. The density is pretty high, but not extremely so. You can expect this coffee will hold well on the shelf.
This lot includes classic Kenyan cultivars SL-28 and SL-34, produced by Scott Laboratories in the 1930s. Both varieties are Bourbon derivations, 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 two 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 steadily increases mirroring the 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 occurred very early in the roast, giving me 1:29 minutes of post crack development time. There were a few super early pops +10 degrees before first crack. On the cupping table this coffee was incredibly sweet. It was juicy like a fruit punch and had the florality of fresh spring blossoms. This coffee has a very elegant and delicate body that is similar to a great Ethiopian coffee. The signature blackberry and pink grapefruit was in perfect harmony. I really love this clean and unique coffee.
This particular Kenyan coffee is a large screen size, but not particularly dense. I decided to use a lower charge temperature of 365F and delayed heat until 2:20 into the roast. Using the Ikawa roast as a guide, I knew that first crack would come early so I wanted to make sure to keep a gentle heat and a slow ramping curb throughout the roast. First crack was extremely early at 389F, which may be the earliest first crack I’ve recorded on the Probatino so far. I reduced the heat a couple of times towards the very end of the roast.
With such an early first crack temperature, it can be tough to decide when to drop the batch and I only had enough green coffee for one small 400g batch. I decided that I wanted to have a minimum of 1 minute post crack development time but for the temperature it can be tough to say. Usually first crack happens around 395F and I drop the batch with a +10F climb at 405F if I want a light and bright coffee. In this scenario I decided to drop the batch at 398F using the +10F logic.
On the cupping table this coffee was lively with lots of grapefruit and pomelo. The base notes were juicy with blackberry and pineapple, reminiscent of fruit punch. The pomelo was quite zesty. If I wanted to eliminate that flavor or round it out, I would not have reduced the heat towards the end and finished the roast at a higher end temperature with the same post crack development time or little less.
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.
This awesomely sweet Kenyan coffee was an interesting one to roast. I knew I was dealing with a relatively dry coffee with lower water activity. The screen size has a very small distribution, and is mostly 18 screen. These stats gave me the impression I would need a little extra energy at the beginning of the roast, and that I’d need to keep the heat on throughout development.
I did want to draw out the drying phase in this coffee a bit, and set the fan to 2 just before the turning point. I waited a bit longer than usual to up the fan speed to 4, as my initial adjustment seemed to have a pronounced effect, leading me to believe attention to fan speed is especially crucial for roasting on the Quest. My final adjustment was to edge off heat application at 356F/7:00 by turning down to 7.5A. Crack started at 375F/8:05 – much earlier than I had anticipated! Make sure to keep the early crack in mind while roasting this coffee, especially if you want to draw out more sugary notes during the Maillard phase. Just after crack, I increased fan speed to full in order to pull chaff to the back of the roaster. Final roast time was 9:35 with a drop temperature of 392.6F.
Distinct lemon and lime flavors came through with this coffee, and a custardy sweetness followed. This coffee has not only great acid expression, but great structure. I do believe that drawing out the Maillard portion of the roast would have added a bit more sugary presence, but I was honestly very happy drinking this coffee as brewed by the esteemed Ms. Loofbourow. Take a look at her notes below for some pointers on brewing this solid Kenyan selection.
This coffee cupped with particularly high acidity and complexity, and since it’s part of our new Red Cherry project I knew that every grain of this coffee was of the highest quality. I posed myself the challenge of achieving very high extractions to get the most out of this beautiful coffee from Nyeri. To aid in this effort, I pulled out the December Dripper, which has adjustable drainage holes to control flow rate; the barista can choose between completely closing off the holes to create a full immersion brew bed, or increasing flow rate by opening between 1 and 3 drainage holes in the bottom of the brewer. This allows for a lot of control over the rate of extraction.
Most weeks, I’m able to use coffee that’s pretty freshly roasted. Due to travel schedules and move in dates, Jen’s Probatino roasts were about 11 days old before I was able to brew them, while Evan’s Quest roast was at day 7. To start, I brewed both roasts to the same recipe to see how they differed from each other. Both came out with pretty high extractions and plenty of vibrant acidity, but there were some great caramelized and fruit sugars as well; notes of brown sugar, lemon lime soda and currant abounded.
Since Evan’s Quest roast showed a little more acidity than I was looking for, I dialed the EK up to 8.5 and lowered the bloom time back down to 30 seconds. This had the end result of extending the brew time, and my percent extraction for this brew wasn’t significantly lower. Nonetheless, this cup was significantly more balanced and sweet, with notes of maple syrup and vanilla balancing out the white grape and cranberry top notes. This is an incredibly clean and dynamic coffee that can be pushed to the extremes to discover more and more layers of flavor.