Fermentation Test Series – Outcomes as of Winter, 2017

We will be hosting a public cupping at our SOMA Cafe to highlight the uniqueness of the El Salvador Buenos Aires Fermentation Test Collection and we hope you will join us! Representatives from both Equator Coffees and Scott Laboratories, a Sonoma-based wine, beer and spirits laboratory, will be on-site for this special tasting experience. 

To get the most out of this blog, we encourage you to also read about the El Salvador Buenos Aires Fermentation Test Collection first. For further context, the coffees in this collection were processed in March of 2016, in Santa Ana, El Salvador. There were three lots in all, one control lot and two lots using different yeast strains, one known as Oro and the other we’re calling L2 (also known as Cima). For more details on how these coffees were processed click the link above. After drying, resting and shipping, the coffees landed on our shore, and we began tasting them shortly thereafter. We intend to continue our sensory evaluation process for many months to come.

Here are our latest findings. We used a “Burundi-style” method of washed processing for each lot. All lots were processed in the exact same way, the only difference was the yeast strains used to control fermentation in two batches.

  • Control Lot -- No yeast was added during the fermentation stage for this lot. At this point, we are finding the control lot to have very good flavor. Of the three lots, this one seems to have the most complexity and balance. It is displaying delicate fruit flavors (honeydew melon and orange,) balanced by milk chocolate sweetness. The coffee we selected for this experiment was impeccably harvested, only ripe Bourbon variety cherries. It is no wonder the coffee is tasting so good.     
  • Oro Yeast – Identical coffee was used for this lot. The only difference in processing is that the Oro yeast strain was activated and then added to the fermentation tank. By adding it at this stage, the yeast outcompeted wild yeasts in the environment. We are finding that this lot tends to be the most mellow and smooth. Although the fruit notes mentioned above are still evident, they are more subdued. Sweetness is the standout in this cup, the flavor turns away from chocolate and takes on more of a caramel-like character.
  • L2 Yeast – As with the Oro lot, all variables were the same except we added the L2 yeast strain to the fermentation tank. In the cup, we have noticed a little less sweetness and a bit more brightness. The fruit flavor is more distinctly citrusy, tending more toward lemon and lime rather than sweeter citrus like the orange notes noticed in the control lot.

This will be the sixth year we have featured coffee from Finca Buenos Aires, each season experimenting with different processing methods. We will be conducting our third yeast test this spring, the details of which haven’t been finalized. With each new test, we strive to learn more about how yeast impacts the flavor of coffee. Since we are starting with a great tasting coffee, the differences we detect with this current collection are subtle, so subtle that the casual coffee drinker might easily overlook them. With careful attention however, the differences noted above will begin to stand out. The best was to taste is in direct comparison – brew three cups and taste them side-by-side!

We will offer this collection of coffees through winter and spring of this year, and continue roasting them for our customers as long as the coffees continue to taste good. We are storing the coffee in GrainPro bags which helps prevent premature fading. To taste along with us, we suggest ordering the collection now and then again in a couple of months to see how the coffees change over time. Even after the coffees are past their prime, we will continue evaluating them at our roastery. Our goal is multifold, not only do we want to know what impact the different yeast strains have on the coffees’ flavor, we also would like to discover if yeast helps preserves the flavor of coffee over time.

Ted Stachura
Director of Coffee
Equator Coffees & Teas