INTRODUCTION BY CHRIS KORNMAN
36574 – Mexico Oaxaca Pluma San Agustín Loxica GrainPro is sourced from Calguera Gomez S.A. De C.V. and thirty-seven surrounding family-owned farms located within the municipality of San Agustín Loxicha in the state of Oaxaca, Mexico. Coffee producers use their own micro-mill to process harvested cherries, which allows for meticulous care in depulping, fermenting, and drying the coffee. Coffee is cultivated on farms that average 10 to 24 acres in size. The Calguera Gomez company aims to organize and support producers with access to the best agricultural practices and consequently pay high prices for higher quality coffee production.
We specifically chose 36574 – Mexico Oaxaca Pluma San Agustín Loxica GrainPro as an example of a high moisture coffee. The coffee’s low density and high water activity and moisture content provide a unique challenge for the roaster; take a look at Jen’s analysis below for some insight as to how to work with a coffee with great flavor potential but less-than-ideal physical traits.
The combination of high moisture and low density in 36574 – Mexico Oaxaca Pluma San Agustín Loxica GrainPro did pose a challenge. I decided to approach it in two ways: aggressive heat versus gentle heat application. A high moisture, high density coffee needs a lot of heat and creates a humid drum for roasting that can lead to low temperature readouts and a stall in the rate of rise if the roaster is not paying attention. Thus requiring aggressive heat application to push the coffee through the roast.
However, the low density nature of our 36574 – Mexico Oaxaca Pluma San Agustín Loxica GrainPro did not create this scenario in the drum and with aggressive heat came a steep rate of rise as seen with PR-0163 in red. Flavors in the cup showed signs of sweetness like toffee and almond or cherry, but also unpleasant flavors like cardboard, tobacco and bitterness that were entirely roaster error.
On my second roast, PR-0164 in white, I lowered the charge temperature and delayed the heat application creating a nice gentle curve. The ratios of my drying stage, Maillard, and development stayed the same, but the overall time of the roast was increased by a full minute. The change in flavor and specifically the sugar browning flavors were greatly improved. Cupping notes of milk chocolate, fudge, and almond made for a sweeter cup with a larger tactile presence on the palate with no roaster defect.
This type of roast comparison is always interesting to me because both roasts are taken to roughly the same end temperature, but how they get there made a big impact. I recommend roasting this coffee in a slow and gentle style, similar to a low density high moisture coffee from Sumatra. The large sweet chocolate notes are perfect for those who want a sweet, low acid coffee. Our 36574 – Mexico Oaxaca Pluma San Agustín Loxica GrainPro would also make a beautiful sweet base blended with a nice high acid Central American or African coffee.
While our main focus on the analysis of 36574 – Mexico Oaxaca Pluma San Agustín Loxica GrainPro this week was on roasting, we went ahead a brewed up a few samples to see how roasts were affected by brewing variables. Brewing Jen’s two roasts side by side in a glass Kalita Wave, Evan produced nearly identical extractions a mere 0.1% difference between the two at identical dose and grind settings.
A second examination of PR-164, Jen’s second roast highlighted above, I used two Chemex brews to create different extraction levels with the same grind setting. A low ratio of coffee to water, around 1:18, produced a really enjoyably clean albeit somewhat thin-bodied brew that landed squarely in the SCAA’s definition of good extraction, yielding 1.27 tds and a slightly high 21.04% extraction. At a much higher dose, more bitterness emerged and the finish became rough and unpleasant. While the extraction of 20.21% seems pretty normal, the 1:14 brew ratio coughed up a hefty 1.62 tds that was definitely stronger than ideal, especially for this coffee.
Keeping this in mind, I wanted to try one more brew with a goal of improving the body. Reverting to the Kalita Wave, I opted to find some middle ground on the dose-to-water ratio, using about 1:16.5 but with a finer-than-average grind. The result yielded a 1.39 tds and a 20.83% extraction. Despite a pretty short brew time, the coffee tasted sweet and fudgy (Jen called it ‘chocolate pudding’) with a full body and almost no bitterness. This was our favorite brew of 36574 – Mexico Oaxaca Pluma San Agustín Loxica GrainPro.
The takeaway here is that under normal brewing parameters this coffee should perform as expected and could be used comfortably in a blend, where it’s middle-of-the-road solubility should play well with other coffees.